22. In the division calculation $952473 \div 18$, which two adjacent digits should be swapped in order to increase the result by 100 ?
A 9 and 5
B 5 and 2
C 2 and 4
D 4 and 7
E 7 and 3
Solution
C If after division by 18 the number has to be increased by 100 , then before the division it needs to be increased by $18 \times 100=1800$. So we need to find two adjacent digits in the number 952473 which when swapped increase it by 1800 .
If 952473 is increased by 1800 it becomes $952473+1800=954273$. We obtain 954273 from 952473 by swapping the adjacent digits 2 and 4 .