OK, let's work through this together. We're starting with 70 and we're going to multiply it by 7, which means we add 70 to itself 7 times.
Step 1: 0 + 70 = 70
Step 2: 70 + 70 = 140
Step 3: 140 + 70 = 210
Step 4: 210 + 70 = 280
Step 5: 280 + 70 = 350
Step 6: 350 + 70 = 420
Step 7: 420 + 70 = 490

So, 70*7 = 490