OK, let's work through this together. We're starting with 340 and we're going to multiply it by 28, which means we add 340 to itself 28 times.
Step 1: 0 + 340 = 340
Step 2: 340 + 340 = 680
Step 3: 680 + 340 = 1020
Step 4: 1020 + 340 = 1360
Step 5: 1360 + 340 = 1700
Step 6: 1700 + 340 = 2040
Step 7: 2040 + 340 = 2380
Step 8: 2380 + 340 = 2720
Step 9: 2720 + 340 = 3060
Step 10: 3060 + 340 = 3400
Step 11: 3400 + 340 = 3740
Step 12: 3740 + 340 = 4080
Step 13: 4080 + 340 = 4420
Step 14: 4420 + 340 = 4760
Step 15: 4760 + 340 = 5100
Step 16: 5100 + 340 = 5440
Step 17: 5440 + 340 = 5780
Step 18: 5780 + 340 = 6120
Step 19: 6120 + 340 = 6460
Step 20: 6460 + 340 = 6800
Step 21: 6800 + 340 = 7140
Step 22: 7140 + 340 = 7480
Step 23: 7480 + 340 = 7820
Step 24: 7820 + 340 = 8160
Step 25: 8160 + 340 = 8500
Step 26: 8500 + 340 = 8840
Step 27: 8840 + 340 = 9180
Step 28: 9180 + 340 = 9520

So, 340*28 = 9520