Let's roll up our sleeves and solve this. We have 138 and we're going to multiply it by 19, essentially adding 138 to itself 19 times.
Step 1: 0 + 138 = 138
Step 2: 138 + 138 = 276
Step 3: 276 + 138 = 414
Step 4: 414 + 138 = 552
Step 5: 552 + 138 = 690
Step 6: 690 + 138 = 828
Step 7: 828 + 138 = 966
Step 8: 966 + 138 = 1104
Step 9: 1104 + 138 = 1242
Step 10: 1242 + 138 = 1380
Step 11: 1380 + 138 = 1518
Step 12: 1518 + 138 = 1656
Step 13: 1656 + 138 = 1794
Step 14: 1794 + 138 = 1932
Step 15: 1932 + 138 = 2070
Step 16: 2070 + 138 = 2208
Step 17: 2208 + 138 = 2346
Step 18: 2346 + 138 = 2484
Step 19: 2484 + 138 = 2622

So, 138*19 = 2622