Mathematics · Grades K–2
Arithmetic · Formula sheet
Rules, conditions and small examples in one printable reference.
Remember this
Addition within ten
Count both groups without counting any item twice.
part + part = whole
7 + 2 = 9
Subtraction within ten
Start with the whole and take away the second number.
whole − removed = remaining
3 − 2 = 1
Addition within twenty
Make ten first when it helps.
a + b = total
12 + 1 = 13
Subtraction within twenty
Check subtraction by adding the result back to the amount removed.
a − b = difference
7 + 9 = 16
Two-digit addition
Regroup ten ones as one ten when needed.
ones + ones; tens + tens
66 + 35 = 101
Two-digit subtraction
Exchange one ten for ten ones when needed.
difference + subtrahend = minuend
13 + 14 = 27
Times tables to twelve
Multiplication represents equal groups.
groups × group size = total
10 × 2 = 20
Balance two sides
Work out one side, then subtract the known part.
a + □ = b + c
13 + 41 − 22 = 32
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.