OK, let's work through this together. We're starting with 535 and we're going to multiply it by 24, which means we add 535 to itself 24 times.
Step 1: 0 + 535 = 535
Step 2: 535 + 535 = 1070
Step 3: 1070 + 535 = 1605
Step 4: 1605 + 535 = 2140
Step 5: 2140 + 535 = 2675
Step 6: 2675 + 535 = 3210
Step 7: 3210 + 535 = 3745
Step 8: 3745 + 535 = 4280
Step 9: 4280 + 535 = 4815
Step 10: 4815 + 535 = 5350
Step 11: 5350 + 535 = 5885
Step 12: 5885 + 535 = 6420
Step 13: 6420 + 535 = 6955
Step 14: 6955 + 535 = 7490
Step 15: 7490 + 535 = 8025
Step 16: 8025 + 535 = 8560
Step 17: 8560 + 535 = 9095
Step 18: 9095 + 535 = 9630
Step 19: 9630 + 535 = 10165
Step 20: 10165 + 535 = 10700
Step 21: 10700 + 535 = 11235
Step 22: 11235 + 535 = 11770
Step 23: 11770 + 535 = 12305
Step 24: 12305 + 535 = 12840

So, 535*24 = 12840