Let's roll up our sleeves and solve this. We have 507 and we're going to multiply it by 20, essentially adding 507 to itself 20 times.
Step 1: 0 + 507 = 507
Step 2: 507 + 507 = 1014
Step 3: 1014 + 507 = 1521
Step 4: 1521 + 507 = 2028
Step 5: 2028 + 507 = 2535
Step 6: 2535 + 507 = 3042
Step 7: 3042 + 507 = 3549
Step 8: 3549 + 507 = 4056
Step 9: 4056 + 507 = 4563
Step 10: 4563 + 507 = 5070
Step 11: 5070 + 507 = 5577
Step 12: 5577 + 507 = 6084
Step 13: 6084 + 507 = 6591
Step 14: 6591 + 507 = 7098
Step 15: 7098 + 507 = 7605
Step 16: 7605 + 507 = 8112
Step 17: 8112 + 507 = 8619
Step 18: 8619 + 507 = 9126
Step 19: 9126 + 507 = 9633
Step 20: 9633 + 507 = 10140

So, 507*20 = 10140