The pattern behind the list
Every answer in the 20 times table ends in 0, so the list is easy to check: the answers are the 2 times table with a zero on the end.
Working out big facts
You do not need to learn all 100 facts by heart. Use the method for the 20 times table instead: 20 is 2 tens, so work out the 2s answer and write a zero on the end.
Work out 2 × 100 = 200, then add a zero: 2000.
20 × 100 = 200 × 10 = 2000