Complete the following pattern: 10, 20, 30, and the missing numbers.
There are nine numbers in the pattern. So we can draw a row of nine squares to help us complete the pattern. The first three numbers are given: 10, 20, and 30. We need to find the next six numbers in the sequence to complete the pattern.
The first question we need to ask is what is the rule. What is the rule of the pattern? Do the numbers increase or decrease each time? And how much do they increase or decrease by? Do the numbers go up or down in ones, twos, fives, or tens?
To help find the rule, we can look at the first three numbers in the sequence. Are the numbers increasing or decreasing? The numbers are getting bigger, which means they are increasing. Are they increasing in ones, twos, fives, or tens? They’re increasing by 10 each time. 20 is 10 more than 10. 30 is 10 more than 20.
As the numbers are increasing by 10 each time, we could say the rule is skip-count in tens. If we skip-count in tens, starting from 10, what would the next number in the sequence be? 10, 20, 30, 40, 50, 60, 70, 80, 90. So to complete the pattern, the missing numbers would be 40, 50, 60, 70, 80, and 90.