Quick tens is a mental math strategy used to make additions and subtractions easier by working with multiples of ten. To use this strategy, the number is first rounded up or down to the nearest ten, and then adjustments are made to the calculation. For example, to add 35 + 18 using quick tens, 35 is rounded up to 40, and 18 is rounded up to 20. Then, 5 is added to 20 to get 25, and 40 is added to 25 to get 65, the sum of 35 and 18. Similarly, to subtract 38 - 14 using quick tens, 38 is rounded d