Add the parts: 3rd grade math lesson

What this lesson shows

Fixes a mistake

(4 × 70) × (4 × 2) multiplies the parts. Add them: 280 + 8.

The worked example

The lesson works this one step by step: 4 × 72. Then your kid tries one like it on paper.

The steps

Guess the size
Split into tens and ones
Multiply each part
Add the parts

Helping at home

Guess the size first: the answer is less than the digit times 100. Split the two-digit number into tens and ones, multiply each part, and add the parts. Check the answer against the guess.

If your kid gets stuck

The answer is less than the digit times 100.

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.

See how Lux works

Standards

Common Core 3.OA.B.5
Apply properties of operations as strategies to multiply and divide. Examples: If 6 × 4 = 24 is known, then 4 × 6 = 24 is also known. (Commutative property of multiplication.) 3 × 5 × 2 can be found by 3 × 5 = 15, then 15 × 2 = 30, or by 5 × 2 = 10, then 3 × 10 = 30. (Associative property of multiplication.) Knowing that 8 × 5 = 40 and 8 × 2 = 16, one can find 8 × 7 as 8 × (5 + 2) = (8 × 5) + (8 × 2) = 40 + 16 = 56. (Distributive property.)

Matches a standard in all 50 states and DCSee each state's code

Alabama MA19.3.5, MA19.3.7a
Alaska 3.OA.5, 3.MD.9.c
Arizona 3.OA.B.5, 3.OA.C.7 *
Arkansas 3.CAR.2, 3.CAR.3
California 3.OA.B.5
Colorado 3.OA.B.5
Connecticut 3.OA.B.5
Delaware 3.OA.B.5
District of Columbia 3.OA.B.5
Florida MA.3.NSO.2.4, MA.3.AR.1.1
Georgia 3.PAR.3.3
Hawaii 3.OA.B.5
Idaho 3.OA.B.5, 3.OA.C.7.b
Illinois 3.OA.B.5
Indiana 4.CA.3, 3.CA.5, 3.CA.6, 3.CA.3
Iowa 3.OA.B.5, 3.OA.C.7
Kansas 3.OA.5, 3.OA.7
Kentucky KY.3.OA.5, KY.3.OA.7
Louisiana 3.OA.B.5
Maine 3.OA.B.5
Maryland 3.NOS.C.4, 3.NOS.E.9.a, 3.NOS.E.9.b, 3.NOS.E.9.c, 4.NOS.C.7.a, 4.NOS.C.7.c
Massachusetts 3.OA.B.5
Michigan 3.OA.B.5
Minnesota 3.1.2.5, 5.2.2.1
Mississippi 3.OA.5, 3.OA.7
Missouri 3.RA.B.6, 3.RA.C.7
Montana MT.3.OA.5, MT.3.MD.7.c
Nebraska 3.A.1.e, 3.A.1.g
Nevada 3.OA.B.5
New Hampshire 3.OA.B.5
New Jersey 3.OA.B.5
New Mexico 3.OA.B.5
New York NY-3.OA.5, NY-3.OA.7.a
North Carolina NC.3.OA.1.b
North Dakota 3.AR.OA.1, 3.AR.OA.2, 4.AR.OA.2, 5.AR.OA.1
Ohio 3.OA.5, 3.MD.7.c
Oklahoma 3.N.2.2, 3.N.2.8, 3.A.2.2, 5.A.2.1
Oregon 3.OA.B.5, 3.OA.C.7
Pennsylvania CC.2.2.3.A.2
Rhode Island 3.OA.B.5, 4.OA.A.3.a
South Carolina 3.PAFR.1.3
South Dakota 3.OA.B.5, 3.OA.C.7.a, 3.OA.C.7.b
Tennessee 3.OA.B.5, 3.OA.C.7, 3.MD.C.7.c
Texas 111.5.b.4.F, 111.5.b.4.G
Utah 3.OA.5, 3.OA.7.b
Vermont 3.OA.B.5
Virginia 3.CE.2c, 3.CE.2d, 3.CE.2f
Washington 3.OA.B.5
West Virginia M.3.5, M.3.7
Wisconsin M.3.OA.C.6, M.3.OA.B.4
Wyoming 3.OA.7, 3.MD.7c, 3.MDP.7.C

Add the parts