Estimating Products Using Compatible Numbers
Estimating Products Using Compatible Numbers is a Grade 4 math skill in enVision Mathematics, Chapter 4: Use Strategies and Properties to Multiply by 2-Digit Numbers. Students replace factors with nearby compatible numbers to quickly estimate multiplication products.
Key Concepts
To estimate a product $a \times b$, replace the factors with nearby compatible numbers, $c$ and $d$, such that $c \approx a$ and $d \approx b$. The estimate is the product $c \times d$.
Common Questions
What are compatible numbers in multiplication?
Compatible numbers are numbers close to the original factors that are easy to multiply mentally, such as multiples of 10 or 25, used to estimate products.
How do you estimate products using compatible numbers?
Replace one or both factors with nearby compatible numbers, then multiply. For example, to estimate 24 times 39, use 25 times 40 to get an estimate of 1,000.
Why use compatible numbers instead of rounding to estimate?
Compatible numbers give you numbers that are especially easy to compute mentally, even if they are not the nearest ten or hundred, resulting in more practical estimates.
What is an example of estimating with compatible numbers?
To estimate 34 times 59, use 35 times 60 equals 2,100. The compatible numbers 35 and 60 are close to the originals and easy to multiply.
What chapter covers estimation with compatible numbers in enVision Grade 4?
Estimating products using compatible numbers is covered in Chapter 4: Use Strategies and Properties to Multiply by 2-Digit Numbers in enVision Mathematics Grade 4.