item 1b .unresolved staff comments not applicable .item 2 .properties our global headquarters are located in chicago , illinois , at 20 south wacker drive .the following is a description of our key locations and facilities .location primary use owned/leased lease expiration approximate size ( in square feet ) ( 1 ) 20 south wacker drive chicago , illinois global headquarters and office space leased 2032 ( 2 ) 512000 141 west jackson chicago , illinois trading floor and office space leased 2027 ( 3 ) 150000 333 s .lasalle chicago , illinois trading floor and office space owned n/a 300000 550 west washington chicago , illinois office space leased 2023 250000 one north end new york , new york trading floor and office space leased 2028 ( 4 ) 240000 . location                               | primary use                          | owned/leased | lease expiration | approximate size ( in square feet ) ( 1 )
20 south wacker drive chicago illinois | global headquarters and office space | leased       | 2032 ( 2 )       | 512000                                   
141 west jacksonchicago illinois       | trading floor and office space       | leased       | 2027 ( 3 )       | 150000                                   
333 s . lasallechicago illinois        | trading floor and office space       | owned        | n/a              | 300000                                   
550 west washingtonchicago illinois    | office space                         | leased       | 2023             | 250000                                   
one north endnew york new york         | trading floor and office space       | leased       | 2028 ( 4 )       | 240000                                   
one new change london                  | office space                         | leased       | 2026             | 58000                                    
data center 3chicagoland area          | business continuity and co-location  | leased       | 2031 ( 5 )       | 83000                                    
bagmane tech park bangalore india      | office space                         | leased       | 2020 ( 6 )       | 72000                                     data center 3 chicagoland area business continuity and co-location leased 2031 ( 5 ) 83000 bagmane tech park bangalore , office space leased 2020 ( 6 ) 72000 ( 1 ) size represents the amount of space leased or owned by us unless otherwise noted .( 2 ) the initial lease expires in 2032 with two consecutive options to extend the term for five years each .( 3 ) the initial lease expires in 2027 and contains options to extend the term and expand the premises .( 4 ) the initial lease expires in 2028 and contains options to extend the term and expand the premises .in 2019 , the premises will be reduced to 225000 square feet .( 5 ) in march 2016 , the company sold its datacenter in the chicago area for $ 130.0 million .at the time of the sale , the company leased back a portion of the property .( 6 ) the initial lease expires in 2020 and contains an option to extend the term as well as an option to terminate early .item 3 .legal proceedings see 201clegal and regulatory matters 201d in note 12 .contingencies to the consolidated financial statements beginning on page 87 for cme group 2019s legal proceedings disclosure which is incorporated herein by reference .item 4 .mine safety disclosures not applicable. .
Question: what square footage will the one north end ny, ny premises be reduced to in 2019?
Steps: Ask for number 225000
Answer: 225000.0
Question: and what is the starting square footage?

Read the following texts and table with financial data from an S&P 500 earnings report carefully.Based on the question-answer history (if provided), answer the last question. The answer may require mathematical calculation based on the data provided.
item 1b .unresolved staff comments not applicable .item 2 .properties our global headquarters are located in chicago , illinois , at 20 south wacker drive .the following is a description of our key locations and facilities .location primary use owned/leased lease expiration approximate size ( in square feet ) ( 1 ) 20 south wacker drive chicago , illinois global headquarters and office space leased 2032 ( 2 ) 512000 141 west jackson chicago , illinois trading floor and office space leased 2027 ( 3 ) 150000 333 s .lasalle chicago , illinois trading floor and office space owned n/a 300000 550 west washington chicago , illinois office space leased 2023 250000 one north end new york , new york trading floor and office space leased 2028 ( 4 ) 240000 . location                               | primary use                          | owned/leased | lease expiration | approximate size ( in square feet ) ( 1 )
20 south wacker drive chicago illinois | global headquarters and office space | leased       | 2032 ( 2 )       | 512000                                   
141 west jacksonchicago illinois       | trading floor and office space       | leased       | 2027 ( 3 )       | 150000                                   
333 s . lasallechicago illinois        | trading floor and office space       | owned        | n/a              | 300000                                   
550 west washingtonchicago illinois    | office space                         | leased       | 2023             | 250000                                   
one north endnew york new york         | trading floor and office space       | leased       | 2028 ( 4 )       | 240000                                   
one new change london                  | office space                         | leased       | 2026             | 58000                                    
data center 3chicagoland area          | business continuity and co-location  | leased       | 2031 ( 5 )       | 83000                                    
bagmane tech park bangalore india      | office space                         | leased       | 2020 ( 6 )       | 72000                                     data center 3 chicagoland area business continuity and co-location leased 2031 ( 5 ) 83000 bagmane tech park bangalore , office space leased 2020 ( 6 ) 72000 ( 1 ) size represents the amount of space leased or owned by us unless otherwise noted .( 2 ) the initial lease expires in 2032 with two consecutive options to extend the term for five years each .( 3 ) the initial lease expires in 2027 and contains options to extend the term and expand the premises .( 4 ) the initial lease expires in 2028 and contains options to extend the term and expand the premises .in 2019 , the premises will be reduced to 225000 square feet .( 5 ) in march 2016 , the company sold its datacenter in the chicago area for $ 130.0 million .at the time of the sale , the company leased back a portion of the property .( 6 ) the initial lease expires in 2020 and contains an option to extend the term as well as an option to terminate early .item 3 .legal proceedings see 201clegal and regulatory matters 201d in note 12 .contingencies to the consolidated financial statements beginning on page 87 for cme group 2019s legal proceedings disclosure which is incorporated herein by reference .item 4 .mine safety disclosures not applicable. .
Question: what square footage will the one north end ny, ny premises be reduced to in 2019?
Steps: Ask for number 225000
Answer: 225000.0
Question: and what is the starting square footage?
