Question Video: Skip Counting Backward by 2s within 1000

When skip counting backward by 2s, subtract 2 each time. Find the missing numbers.

02:51

Video Transcript

When skip counting backward by twos, subtract two each time. Find the missing numbers.

In this question, we’re given a number pattern to complete. And we’re told the rule is to subtract two each time. We have to find the missing numbers in the pattern and select the correct number line out of the four number lines we’ve been given. The first two numbers in the sequence have been given. 729 subtract two is 727. So to find the next number, we need to subtract two from 727, which is 725. Two less than 725 is 723, and two less than 723 is 721. And the final number in the sequence must be 719, which is two less than 721.

Which of the four number lines we’ve been given is correct? It’s not the first number line. It goes 729, 727, 722. We’ve gone wrong here. They subtracted five from 727. This is not the correct answer. Let’s look at the second number line. We’ve got 729 take away two gives us 727, but 727 take away two isn’t 726. They’ve only subtracted one. This number line is not correct either. How about this one? 729, 727, 729. Wait, that’s not right. They’ve added two to 727, and they kept on adding two. This number line is not correct either. How about the last number line? 729 and 727, 725, 723, 721, 719. This is the correct number line. The pattern follows the rule, to subtract two each time. So this is the number line which correctly followed the rule for the pattern, to subtract two each time.

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