Alright, let's solve this math problem step by step. First, we have the number 390. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 23. So, we're going to take the number 390 and add it to itself 23 times.
Step 1: 0 + 390 = 390
Step 2: 390 + 390 = 780
Step 3: 780 + 390 = 1170
Step 4: 1170 + 390 = 1560
Step 5: 1560 + 390 = 1950
Step 6: 1950 + 390 = 2340
Step 7: 2340 + 390 = 2730
Step 8: 2730 + 390 = 3120
Step 9: 3120 + 390 = 3510
Step 10: 3510 + 390 = 3900
Step 11: 3900 + 390 = 4290
Step 12: 4290 + 390 = 4680
Step 13: 4680 + 390 = 5070
Step 14: 5070 + 390 = 5460
Step 15: 5460 + 390 = 5850
Step 16: 5850 + 390 = 6240
Step 17: 6240 + 390 = 6630
Step 18: 6630 + 390 = 7020
Step 19: 7020 + 390 = 7410
Step 20: 7410 + 390 = 7800
Step 21: 7800 + 390 = 8190
Step 22: 8190 + 390 = 8580
Step 23: 8580 + 390 = 8970

So, 390*23 = 8970