You are watching: How to estimate using compatible numbers
Using the number above, we have the right to make the complying with conclusions around compatible numbers:
Estimating sumsFives room compatible: 75 + 25 = 100Any numbers that make tens space compatible. 32 + 48 = 80
Estimating differencesNumbers with the same last digit or digits are compatible: 72 - 52.Numbers that end with 1 or more zeros space compatible. For example, usage 200 - 100 to calculation 198 - 99.
Estimating products and quotients.Numbers that finish with 1 or an ext zeros are compatible. Numbers in the multiplication table assuming that we recognize the table by heart.
Some instances of compatible numbers as soon as doing division are 400 and 10, 36 and also 6, 2400 and 12, and also 64 and 8.
2400 and 12 are compatible due to the fact that when act this division (2400/12), us can quickly divide 24 through 12 to get 2 and put two zeros in ~ the finish to gain 200.
Some instances of compatible numbers as soon as doing multiplication are 200 and 40, 1100 and also 40, 25 and also 4.
1100 and 40 space compatible since we can quickly do this multiplication by multiply 11 and 4 to get 44 and include three zeros at the finish to acquire 44000.
Some instances of compatible numbers as soon as doing addition are 225 and 75, 298 and also 2, and also 540 and also 60.Some examples of compatible numbers when doing subtraction are 435 and 25, 800 and also 600, and also 5986 and also 2986.
When estimating, save in mind that we room not explain the answer will be exact. We space just in search of a reasonable estimate.
When estimating through division, if friend decrease the value of one number, friend should additionally decrease the value of the other. If you boost the worth of one number, you should rise the value of the other.
This helps to save the estimate as close as feasible to the specific answer.
Estimate the following division using compatible numbers1. 232 ÷ 11 2. 3421 ÷ 9 3. 25889 ÷ 521. Compatible numbers because that 232 and also 11 are 240 and 12. An alert that both numbers were increased! 24 can be separated by 12 to get 2. Then, include a zero at the finish to gain 202. Compatible numbers because that 3421 and also 9 are 3200 and 8. 32 deserve to be divided by 8 to obtain 4. Then include one zero at the finish to acquire 400 400 is a reasonable estimate. 3321 ÷ 9 = 369 and 369 have the right to be rounded come the nearest hundreds to 4003. Compatible numbers because that 25889 and 52 room 25000 and 50 When dividing 25000 by 50, the zero next to 50 cancels out through one zero of 25000, for this reason the problem becomes 2500 ÷ 5 25 ÷ 5 = 5. Then, add two zeros at the end and also the answer is 500 500 is a reasonable estimate since 25889 ÷ 52 = 497.86 and also 497.86 is close come 500
Estimate the adhering to multiplication using compatible numbers1.72 × 78 2. 288 × 4151. Compatible numbers for 72 and also 78 space 70 and also 80. Note that one number was lessened while the other was increased!Multiply 7 by 8 and add two zeros in ~ the end to acquire 56002.Compatible numbers because that 288 and also 415 are 300 and also 400Multiply 3 by 4 and add four zeros in ~ the end to get 120000.Now, if ns ask the inquiry again, what room compatible numbers, would you be able to answer v confidence?If not, simply study again! So, what space compatible numbers? simply kidding!
What are compatible numbers? take it the quiz below to see how well you know compatible numbers.
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