Written Multiplication & Division
Write and calculate mathematical statements for multiplication and division using known tables, including two-digit × one-digit, using mental and progressing to formal written methods
کارهایی که یادگیرنده بعد از این درس می‌تواند انجام دهد
- Calculate 23 × 4 using partitioning (20 × 4 + 3 × 4)
- Calculate 96 ÷ 8 using known table facts
- Begin to use a formal written layout for short multiplication
۱ · بخوان
Priya's array showed how 2 × 5 = 10 tells the story of rows. Party bags need bigger stories, like 23 × 4 treats or 96 sweets shared as 96 ÷ 8. The trick for multiplying is to split the big number into tens and ones, work out each piece, then add the pieces back together.
To work out 23 × 4, split 23 into 20 and 3. First, 20 × 4 = 80. Then, 3 × 4 = 12. Add the two parts: 80 + 12 = 92. So 23 × 4 = 92.
Grown-ups often write multiplication in columns, like a small tower of numbers. You multiply the ones digit first, write down the ones part of the answer, and carry any tens into the next column. It looks different, but it does the same job as splitting the number.
Division uses your table facts too. To work out 96 ÷ 8, ask: what times 8 makes 96? You know 8 × 12 = 96, so 96 ÷ 8 = 12. If that feels too big, split it: 96 is 80 + 16. 80 ÷ 8 = 10 and 16 ÷ 8 = 2, so 10 + 2 = 12.
Split big numbers into tens and ones, multiply or divide each part with your tables, then put the parts back together.
The rewritten readings were written for this dataset.
برای خواندن بیشتر
Multiply a number in smaller parts
Try 23 x 4 by breaking 23 into 20 + 3. Multiply each part: 20 x 4 = 80 and 3 x 4 = 12. Now add 80 + 12 = 92. This is called partitioning. Written multiplication puts these calculations into columns, starting with the ones.
Use multiplication to help you divide
To solve 96 / 8, ask, "What number times 8 makes 96?" You know 8 x 12 = 96, so 96 / 8 = 12. Practising times tables both ways helps with larger divisions. Dividing asks you to find a missing number in a multiplication.
Apply place value strategies to multiply three-digit numbers by one-digit numbers
Place value powers written multiplication. Multiplying 23 by 4 means 4 lots of 3 ones plus 4 lots of 2 tens. The ones give 12, so write 2 and regroup 1 ten. The tens give 8 plus the regrouped 1, making 9. Lining digits by worth keeps every ten in its place.
Strategies for dividing
Clever dividing tries friendly chunks first. To split 96 eight ways, peel off 80 (ten each) and share the 16 left (two each). Ten plus two is 12 each. Chunking, tables and short layouts all reach the same answer. Pick the route you trust and check by multiplying back.
کاوش بیشتر
۲ · ببین
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