Let's roll up our sleeves and solve this. We have 457 and we're going to multiply it by 7, essentially adding 457 to itself 7 times.
Step 1: 0 + 457 = 457
Step 2: 457 + 457 = 914
Step 3: 914 + 457 = 1371
Step 4: 1371 + 457 = 1828
Step 5: 1828 + 457 = 2285
Step 6: 2285 + 457 = 2742
Step 7: 2742 + 457 = 3199

So, 457*7 = 3199