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fact-minute

Grades 1–5 · printable + timed

Subtracting 12 Timed Test

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

Operation
Fact range
Problems
Time limit

Subtraction · 12s · 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 · 12s · 20 problems NameDate
  1. 1 20 − 8 12
  2. 2 14 − 2 12
  3. 3 22 − 12 10
  4. 4 23 − 11 12
  5. 5 12 − 0 12
  6. 6 20 − 12 8
  7. 7 17 − 5 12
  8. 8 19 − 7 12
  9. 9 16 − 12 4
  10. 10 15 − 3 12
  11. 11 12 − 0 12
  12. 12 24 − 12 12
  13. 13 18 − 6 12
  14. 14 13 − 12 1
  15. 15 13 − 1 12
  16. 16 17 − 12 5
  17. 17 23 − 12 11
  18. 18 16 − 12 4
  19. 19 16 − 12 4
  20. 20 13 − 1 12
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 12

Subtracting 12, from 12 − 12 to 24 − 12. 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 12: all thirteen facts and their answers.
Problem Answer
12 − 12 0
13 − 12 1
14 − 12 2
15 − 12 3
16 − 12 4
17 − 12 5
18 − 12 6
19 − 12 7
20 − 12 8
21 − 12 9
22 − 12 10
23 − 12 11
24 − 12 12

Where subtracting 12 goes wrong

Taking 12 away means splitting it into 10 and 2 — 19 − 12 goes to 9 then 7 — and either step can carry a borrow, which is why this range automates last in the subtraction set. An answer roughly 10 too high says the tens step was skipped rather than that the fact is unknown.

Three that come up

How do you subtract 12?
Take 10, then take 2. 20 − 12 goes 10, then 8.
Why is this the last table to become automatic?
Two steps, each able to borrow, gives the answer more ways to go wrong.
What does an error of about ten mean?
Only the 2 was subtracted and the tens step was dropped.

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