Let's roll up our sleeves and solve this. We have 343 and we're going to multiply it by 11, essentially adding 343 to itself 11 times.
Step 1: 0 + 343 = 343
Step 2: 343 + 343 = 686
Step 3: 686 + 343 = 1029
Step 4: 1029 + 343 = 1372
Step 5: 1372 + 343 = 1715
Step 6: 1715 + 343 = 2058
Step 7: 2058 + 343 = 2401
Step 8: 2401 + 343 = 2744
Step 9: 2744 + 343 = 3087
Step 10: 3087 + 343 = 3430
Step 11: 3430 + 343 = 3773

So, 343*11 = 3773