Alright, let's solve this math problem step by step. First, we have the number 135. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 42. So, we're going to take the number 135 and add it to itself 42 times.
Step 1: 0 + 135 = 135
Step 2: 135 + 135 = 270
Step 3: 270 + 135 = 405
Step 4: 405 + 135 = 540
Step 5: 540 + 135 = 675
Step 6: 675 + 135 = 810
Step 7: 810 + 135 = 945
Step 8: 945 + 135 = 1080
Step 9: 1080 + 135 = 1215
Step 10: 1215 + 135 = 1350
Step 11: 1350 + 135 = 1485
Step 12: 1485 + 135 = 1620
Step 13: 1620 + 135 = 1755
Step 14: 1755 + 135 = 1890
Step 15: 1890 + 135 = 2025
Step 16: 2025 + 135 = 2160
Step 17: 2160 + 135 = 2295
Step 18: 2295 + 135 = 2430
Step 19: 2430 + 135 = 2565
Step 20: 2565 + 135 = 2700
Step 21: 2700 + 135 = 2835
Step 22: 2835 + 135 = 2970
Step 23: 2970 + 135 = 3105
Step 24: 3105 + 135 = 3240
Step 25: 3240 + 135 = 3375
Step 26: 3375 + 135 = 3510
Step 27: 3510 + 135 = 3645
Step 28: 3645 + 135 = 3780
Step 29: 3780 + 135 = 3915
Step 30: 3915 + 135 = 4050
Step 31: 4050 + 135 = 4185
Step 32: 4185 + 135 = 4320
Step 33: 4320 + 135 = 4455
Step 34: 4455 + 135 = 4590
Step 35: 4590 + 135 = 4725
Step 36: 4725 + 135 = 4860
Step 37: 4860 + 135 = 4995
Step 38: 4995 + 135 = 5130
Step 39: 5130 + 135 = 5265
Step 40: 5265 + 135 = 5400
Step 41: 5400 + 135 = 5535
Step 42: 5535 + 135 = 5670

So, 135*42 = 5670