Sure thing! We've got 783 and we're gonna multiply it by 15. That's the same as adding 783 to itself 15 times.
Step 1: 0 + 783 = 783
Step 2: 783 + 783 = 1566
Step 3: 1566 + 783 = 2349
Step 4: 2349 + 783 = 3132
Step 5: 3132 + 783 = 3915
Step 6: 3915 + 783 = 4698
Step 7: 4698 + 783 = 5481
Step 8: 5481 + 783 = 6264
Step 9: 6264 + 783 = 7047
Step 10: 7047 + 783 = 7830
Step 11: 7830 + 783 = 8613
Step 12: 8613 + 783 = 9396
Step 13: 9396 + 783 = 10179
Step 14: 10179 + 783 = 10962
Step 15: 10962 + 783 = 11745

So, 783*15 = 11745