Montana Math MT.1.NBT.6
The Standard
Subtract multiples of 10 from a two-digit number.
2026 Montana Mathematics Content Standards
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students take away whole tens from numbers like 63. They keep track of the tens that remain and leave the ones unchanged.
What Mastery Looks Like
- A student can show 64 − 20 with blocks or a drawing and get 44. They can explain that two tens were removed and four ones stayed.
Common Misconceptions
- Some students treat 20 as 2 and answer 61 for 63 − 20. Others remove the ones too and answer 40.
How to Assess It
- Ask students to solve 68 − 30. Have them draw tens and ones, then circle what they removed.
Lesson moves
Ways to Teach It
Build 67 with base-ten blocks, remove two ten-rods, and record how many tens and ones remain.
Ask, “Why do the six ones stay the same in 56 − 30?” Have students write one sentence.
Give pairs number cards marked 46, 57, and 68 and subtraction cards marked 10, 20, and 30 to match and solve.
Tell students a box holds 75 pencils and a teacher gives away 20; have them draw and solve for the pencils left.
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Printable MT.1.NBT.6 Worksheet
A ready-to-print activity worksheet aligned to MT.1.NBT.6, with an answer key for the teacher on its own page. No account needed.
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