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fact-minute

Grades 1–5 · printable + timed

Subtracting 8 Timed Test

Print it with the answer key on page 2, or run the timer here.

Operation
Fact range
Problems
Time limit

Subtraction · 8s · 20 problems · 1 minute NameDateScore
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12
  13. 13
  14. 14
  15. 15
  16. 16
  17. 17
  18. 18
  19. 19
  20. 20
Answer key · Subtraction · 8s · 20 problems NameDate
  1. 1 14 − 8 6
  2. 2 14 − 8 6
  3. 3 20 − 12 8
  4. 4 11 − 8 3
  5. 5 17 − 8 9
  6. 6 13 − 5 8
  7. 7 11 − 8 3
  8. 8 17 − 9 8
  9. 9 12 − 8 4
  10. 10 10 − 2 8
  11. 11 8 − 8 0
  12. 12 10 − 8 2
  13. 13 10 − 8 2
  14. 14 14 − 6 8
  15. 15 13 − 5 8
  16. 16 13 − 5 8
  17. 17 11 − 8 3
  18. 18 15 − 7 8
  19. 19 19 − 8 11
  20. 20 10 − 8 2
0 correct of 20

Correct 0 Wrong 0 Blank 20

0:00 elapsed of 1:00

Elapsed 0s Left 60s

A timed sheet on subtracting 8

Subtracting 8, from 8 − 8 to 20 − 8. Every problem on the sheet is drawn from that set and nothing outside it.

Choose 20, 50 or 100 problems and a limit of 1, 2 or 5 minutes, then print the sheet with its answer key on page two, or start the timer and type into the same grid. The problems are drawn again every time the page loads, so a second sheet is not a copy of the first. How the counts and limits work is on its own page, along with what a timed test does and does not measure.

Thirteen rows, with the answers

Subtracting 8: all thirteen facts and their answers.
Problem Answer
8 − 8 0
9 − 8 1
10 − 8 2
11 − 8 3
12 − 8 4
13 − 8 5
14 − 8 6
15 − 8 7
16 − 8 8
17 − 8 9
18 − 8 10
19 − 8 11
20 − 8 12

Where subtracting 8 goes wrong

The quickest way to take 8 away is to take 10 and give 2 back — 15 − 8 = 5 + 2 = 7. Because the amount given back is 2, errors in this range come out two too small. A sheet consistently two low means the child took the ten and stopped there, which is a missing step rather than a missing fact.

Three that come up

What is the quickest way to subtract 8?
Subtract 10 and add 2 back. 16 − 8 becomes 6 + 2 = 8.
My child is two too low every time. Why?
They subtracted 10 and stopped. The error equals the step that was skipped.
Is going down to ten better?
Both work. Subtract-ten is faster once adding a small amount back is comfortable.

What the standards and the critics actually say

Common Core State Standards for Mathematics (PDF), page 19 — 2.OA.B.2 “By end of Grade 2, know from memory all sums of two one-digit numbers.” thecorestandards.org — CCSSI_Math Standards.pdf

NCTM — Procedural Fluency in Mathematics (position statement) “Timed tests do not assess fluency and can negatively affect students, and thus should be avoided.” nctm.org — Procedural Fluency in Mathematics

youcubed — Fluency Without Fear “For about one third of students the onset of timed testing is the beginning of math anxiety.” youcubed.org — Fluency Without Fear