Let's roll up our sleeves and solve this. We have 240 and we're going to multiply it by 57, essentially adding 240 to itself 57 times.
Step 1: 0 + 240 = 240
Step 2: 240 + 240 = 480
Step 3: 480 + 240 = 720
Step 4: 720 + 240 = 960
Step 5: 960 + 240 = 1200
Step 6: 1200 + 240 = 1440
Step 7: 1440 + 240 = 1680
Step 8: 1680 + 240 = 1920
Step 9: 1920 + 240 = 2160
Step 10: 2160 + 240 = 2400
Step 11: 2400 + 240 = 2640
Step 12: 2640 + 240 = 2880
Step 13: 2880 + 240 = 3120
Step 14: 3120 + 240 = 3360
Step 15: 3360 + 240 = 3600
Step 16: 3600 + 240 = 3840
Step 17: 3840 + 240 = 4080
Step 18: 4080 + 240 = 4320
Step 19: 4320 + 240 = 4560
Step 20: 4560 + 240 = 4800
Step 21: 4800 + 240 = 5040
Step 22: 5040 + 240 = 5280
Step 23: 5280 + 240 = 5520
Step 24: 5520 + 240 = 5760
Step 25: 5760 + 240 = 6000
Step 26: 6000 + 240 = 6240
Step 27: 6240 + 240 = 6480
Step 28: 6480 + 240 = 6720
Step 29: 6720 + 240 = 6960
Step 30: 6960 + 240 = 7200
Step 31: 7200 + 240 = 7440
Step 32: 7440 + 240 = 7680
Step 33: 7680 + 240 = 7920
Step 34: 7920 + 240 = 8160
Step 35: 8160 + 240 = 8400
Step 36: 8400 + 240 = 8640
Step 37: 8640 + 240 = 8880
Step 38: 8880 + 240 = 9120
Step 39: 9120 + 240 = 9360
Step 40: 9360 + 240 = 9600
Step 41: 9600 + 240 = 9840
Step 42: 9840 + 240 = 10080
Step 43: 10080 + 240 = 10320
Step 44: 10320 + 240 = 10560
Step 45: 10560 + 240 = 10800
Step 46: 10800 + 240 = 11040
Step 47: 11040 + 240 = 11280
Step 48: 11280 + 240 = 11520
Step 49: 11520 + 240 = 11760
Step 50: 11760 + 240 = 12000
Step 51: 12000 + 240 = 12240
Step 52: 12240 + 240 = 12480
Step 53: 12480 + 240 = 12720
Step 54: 12720 + 240 = 12960
Step 55: 12960 + 240 = 13200
Step 56: 13200 + 240 = 13440
Step 57: 13440 + 240 = 13680

So, 240*57 = 13680