What this lesson shows
Fixes a mistake
325 + 37 is the same as 37 + 325. But 325 − 37 starts from 325, never from 37. Only adding turns around.
The worked example
The lesson works this one step by step: 325 − 37. Then your kid tries one like it on paper.
The steps
- Adding turns around
- Subtracting does not
- Start from the first number
Helping at home
Adding works in either order, but subtracting starts from the first number. Take away to the hundred first, then the rest.
If your kid gets stuck
Start from the first number.
Watch it with Lux
With Lux, this lesson is a narrated video and a printed page your kid works on. Then Lux helps with the same math on their own worksheet, one question at a time.
Standards
- Common Core 2.NBT.B.7
Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.
Matches standards in 45 statesSee each state's code
- Alabama MA19.2.12a
- Alaska 2.NBT.7
- Arizona 2.NBT.B.7
- Arkansas 2.CAR.6
- California 2.NBT.B.7
- Colorado 2.NBT.B.7
- Connecticut 2.NBT.B.7
- Delaware 2.NBT.B.7
- District of Columbia 2.NBT.B.7
- Florida MA.2.NSO.2.4
- Hawaii 2.NBT.B.7
- Idaho 2.NBT.B.7.a, 2.NBT.B.7.b
- Illinois 2.NBT.B.7
- Indiana 2.CA.2
- Iowa 2.NBT.B.7
- Kansas 2.NBT.7
- Kentucky KY.2.NBT.7.a, KY.2.NBT.7.b
- Louisiana 2.NBT.B.7
- Maine 2.NBT.B.7
- Maryland 2.NOS.C.9.a, 2.NOS.C.9.b, 2.NOS.C.9.c, 2.NOS.C.9.d
- Massachusetts 2.NBT.B.7
- Michigan 2.NBT.B.7
- Mississippi 2.NBT.7
- Missouri 2.NBT.B.8
- Montana MT.2.NBT.7
- Nebraska 2.N.4.e
- Nevada 2.NBT.B.7
- New Hampshire 2.NBT.B.7
- New Jersey 2.NBT.B.7
- New Mexico 2.NBT.B.7
- New York NY-2.NBT.7.a, NY-2.NBT.7.b
- North Carolina NC.2.NBT.7.a, NC.2.NBT.7.b, NC.2.NBT.7.c, NC.2.NBT.7.d
- Ohio 2.NBT.7
- Oregon 2.NBT.B.7
- Pennsylvania CC.2.1.2.B.3
- Rhode Island 2.NBT.B.7
- South Dakota 2.NBT.B.7
- Tennessee 2.NBT.C.7
- Texas 111.4.b.4.C, 111.4.b.4.D
- Utah 2.NBT.7
- Vermont 2.NBT.B.7
- Washington 2.NBT.B.7
- West Virginia M.2.12
- Wisconsin M.2.NBT.B.7
- Wyoming 2.NBT.7a, 2.NBT.7b, 2.NBT.7c, 2.NBTP.7.A, 2.NBTP.7.B, 2.NBTP.7.C
More in this unit
- Numbers to 1,000 three ways
- What is a digit worth?
- Zero holds the tens place
- Many names for one number
- New names, same number
- Comparing three-digit numbers
- Plot and order on a number line
- Same digits, different places
- Read the line's labels
- Ten more, a hundred more
- Ten more past a hundred
- Adding to 1,000
- Subtracting to 1,000
- Trade only when you need to
- Skip-count past a hundred
- Counting by 25s
- Which estimate makes sense?