OK, let's work through this together. We're starting with 715 and we're going to multiply it by 18, which means we add 715 to itself 18 times.
Step 1: 0 + 715 = 715
Step 2: 715 + 715 = 1430
Step 3: 1430 + 715 = 2145
Step 4: 2145 + 715 = 2860
Step 5: 2860 + 715 = 3575
Step 6: 3575 + 715 = 4290
Step 7: 4290 + 715 = 5005
Step 8: 5005 + 715 = 5720
Step 9: 5720 + 715 = 6435
Step 10: 6435 + 715 = 7150
Step 11: 7150 + 715 = 7865
Step 12: 7865 + 715 = 8580
Step 13: 8580 + 715 = 9295
Step 14: 9295 + 715 = 10010
Step 15: 10010 + 715 = 10725
Step 16: 10725 + 715 = 11440
Step 17: 11440 + 715 = 12155
Step 18: 12155 + 715 = 12870

So, 715*18 = 12870