Let's roll up our sleeves and solve this. We have 40 and we're going to multiply it by 65, essentially adding 40 to itself 65 times.
Step 1: 0 + 40 = 40
Step 2: 40 + 40 = 80
Step 3: 80 + 40 = 120
Step 4: 120 + 40 = 160
Step 5: 160 + 40 = 200
Step 6: 200 + 40 = 240
Step 7: 240 + 40 = 280
Step 8: 280 + 40 = 320
Step 9: 320 + 40 = 360
Step 10: 360 + 40 = 400
Step 11: 400 + 40 = 440
Step 12: 440 + 40 = 480
Step 13: 480 + 40 = 520
Step 14: 520 + 40 = 560
Step 15: 560 + 40 = 600
Step 16: 600 + 40 = 640
Step 17: 640 + 40 = 680
Step 18: 680 + 40 = 720
Step 19: 720 + 40 = 760
Step 20: 760 + 40 = 800
Step 21: 800 + 40 = 840
Step 22: 840 + 40 = 880
Step 23: 880 + 40 = 920
Step 24: 920 + 40 = 960
Step 25: 960 + 40 = 1000
Step 26: 1000 + 40 = 1040
Step 27: 1040 + 40 = 1080
Step 28: 1080 + 40 = 1120
Step 29: 1120 + 40 = 1160
Step 30: 1160 + 40 = 1200
Step 31: 1200 + 40 = 1240
Step 32: 1240 + 40 = 1280
Step 33: 1280 + 40 = 1320
Step 34: 1320 + 40 = 1360
Step 35: 1360 + 40 = 1400
Step 36: 1400 + 40 = 1440
Step 37: 1440 + 40 = 1480
Step 38: 1480 + 40 = 1520
Step 39: 1520 + 40 = 1560
Step 40: 1560 + 40 = 1600
Step 41: 1600 + 40 = 1640
Step 42: 1640 + 40 = 1680
Step 43: 1680 + 40 = 1720
Step 44: 1720 + 40 = 1760
Step 45: 1760 + 40 = 1800
Step 46: 1800 + 40 = 1840
Step 47: 1840 + 40 = 1880
Step 48: 1880 + 40 = 1920
Step 49: 1920 + 40 = 1960
Step 50: 1960 + 40 = 2000
Step 51: 2000 + 40 = 2040
Step 52: 2040 + 40 = 2080
Step 53: 2080 + 40 = 2120
Step 54: 2120 + 40 = 2160
Step 55: 2160 + 40 = 2200
Step 56: 2200 + 40 = 2240
Step 57: 2240 + 40 = 2280
Step 58: 2280 + 40 = 2320
Step 59: 2320 + 40 = 2360
Step 60: 2360 + 40 = 2400
Step 61: 2400 + 40 = 2440
Step 62: 2440 + 40 = 2480
Step 63: 2480 + 40 = 2520
Step 64: 2520 + 40 = 2560
Step 65: 2560 + 40 = 2600

So, 40*65 = 2600