OK, let's work through this together. We're starting with 783 and we're going to multiply it by 27, which means we add 783 to itself 27 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
Step 16: 11745 + 783 = 12528
Step 17: 12528 + 783 = 13311
Step 18: 13311 + 783 = 14094
Step 19: 14094 + 783 = 14877
Step 20: 14877 + 783 = 15660
Step 21: 15660 + 783 = 16443
Step 22: 16443 + 783 = 17226
Step 23: 17226 + 783 = 18009
Step 24: 18009 + 783 = 18792
Step 25: 18792 + 783 = 19575
Step 26: 19575 + 783 = 20358
Step 27: 20358 + 783 = 21141

So, 783*27 = 21141