Counting by Tens with numbers
10, 20, 30, 40, 50, 60, 70, 80, 90
Counting by Tens with words
ten, twenty, thirty, forty, fifty, sixty, seventy, eighty, ninety, one hundred
Number Patterns when counting by Tens
When you count by tens the numbers create a pattern. All the numbers end with a zero. The first digits are just like the numbers when you count (1, 2, 3, 4, 5, etc.). This pattern gives the numbers 10, 20, 30, 40, 50, etc.
found from: http://www.aaamath.com/k4c_cox1.htm
If we're going off of the blue shaded region, the area of the full circle is 254.47 cm^2. Then we calculate the area of the inner circle. This gives you 113.1. Now you must subtract the area of the inner circle by the area of the outer circle. 254.47-113.1. This gives you 141.37, which should be your answer.
