Number and Operations in Base Ten: Multiplying Multi-Digit Numbers Using Place Value and Arrays (CCSS.4.NBT.5)
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4th Grade Math › Number and Operations in Base Ten: Multiplying Multi-Digit Numbers Using Place Value and Arrays (CCSS.4.NBT.5)
What is the product? Use an area model by decomposing the tens and ones: $23 \times 6$
128
138
126
120
Explanation
Think of $23$ as $20+3$. Area model: $20 \times 6 = 120$ and $3 \times 6 = 18$. Add the partial products: $120 + 18 = 138$.
A baker packs 47 cookies in each box. There are 6 boxes. What is the product $47 \times 6$?
242
246
292
282
Explanation
Decompose $47$ into $40+7$. Compute $40 \times 6 = 240$ and $7 \times 6 = 42$. Add: $240 + 42 = 282$.
Find the product using an area model: $23 \times 15$
345
275
335
3450
Explanation
Decompose as $(20+3)(10+5)$. Partial products: $20 \times 10 = 200$, $20 \times 5 = 100$, $3 \times 10 = 30$, and $3 \times 5 = 15$. Sum: $200 + 100 + 30 + 15 = 345$. Or use $23 \times (10+5) = 230 + 115 = 345$.
Find the product using a rectangular area model: $24 \times 18$
400
392
432
472
Explanation
Decompose $(20+4)(10+8)$. Partial products: $20 \times 10 = 200$, $20 \times 8 = 160$, $4 \times 10 = 40$, and $4 \times 8 = 32$. Add: $200 + 160 + 40 + 32 = 432$.