1st Grade · Math · Parent guide
Short answer. This standard asks first graders to find 10 more or 10 less than a number in their heads, no counting. Why it matters and quick ways to practice it at home.
Quick answer
Given any two-digit number, your child should be able to say what is 10 more and what is 10 less, mentally, without counting up or down by ones. So 10 more than 62 is 72, right away, because only the tens digit changes. He also needs to be able to explain that reasoning, not just produce the answer.
Why parents see this skill
Jumping by tens is the first real mental math skill, and it is a direct payoff of place value understanding. It feeds straight into adding and subtracting multiples of 10, using hundreds charts, counting money, and eventually the mental flexibility to solve 62 + 19 as 62 + 20 - 1. Kids who count by ones for everything run out of steam as numbers get bigger.
For reference
Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.Official Common Core source
See it, then try it
You do not need a lesson plan. Look for these signs in ordinary play, reading, and conversation, then choose one short activity.
Tell your child he runs an elevator in a 120-floor building that only moves 10 floors at a time. Call out a floor: you are on 34, someone presses up! He answers 44. Then down twice: 34. Kids will play this far longer than they would answer flashcards with the same math.
Write the numbers 1 to 100 in a 10-by-10 grid, or have your child help fill one in. Put a penny on any number and ask him to move it 10 more or 10 less. He will see it moves exactly one row down or up. That picture is the reasoning the standard wants him to explain.
Build a number with dimes and pennies, like 57. Then add one dime and ask for the new total, no recounting allowed. Take a dime away, ask again. Two minutes of this after dinner, a few times a week, makes the pattern automatic.
Choose what helps today
Start with the domain guide for context, use the learning library when a concept needs explaining, or print a page when your child is ready to practice.
See every 1.NBT skill in order and how the codes fit together.
Open resourceFilter free pages by the exact math skill your child is practicing.
Open resourceExplore number meaning, formation, examples, and printable practice.
Open resourceA short sequence of related early-math pages for repeated practice.
Open resourceParent-friendly ideas for practicing early math in everyday routines.
Open resourceMy son counts up ten times on his fingers to get the answer. Does that count?
It gets the right number, but it is exactly what this standard is trying to move past. The phrase in the standard is 'without having to count.' Do not scold the finger counting; instead give him tools that make the shortcut visible, like a hundreds chart where 10 more is simply the next row down. Once he sees the pattern, the fingers usually retire on their own.
Is my child behind if this is not automatic by mid-year?
This skill usually firms up in the second half of first grade, after place value work has sunk in, so mid-year wobbles are normal. If he can build numbers with tens and ones but has not connected that to quick ten-jumps yet, a couple weeks of short daily practice typically closes the gap. Mention it at conferences if you are unsure how he compares.
Keep the sequence
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