Adding by tens is a mental math strategy that involves breaking down a larger addition problem into smaller steps using multiples of ten. To use this strategy, the larger number is rounded up or down to the nearest ten, and then adjustments are made to the calculation. For example, to add 27 + 48 using adding by tens, 27 is rounded up to 30, and 48 is rounded up to 50. Then, 3 is added to 50 to get 53, the sum of 27 and 50. This strategy helps to simplify the addition process by reducing the number of steps required and is useful in developing mental math skills and increasing fluency in addition.

• Complete the number bonds and number sentences to match the picture.