Multiply 1-digit numbers by decimal fractions using written methods | Maths

Starter quiz

Match the equation to its answer.
- 1.3 × 10 =
  
  ⇔
  
  13 ✓
- 12.9 × 10 =
  
  ⇔
  
  129 ✓
- 1.39 × 100 =
  
  ⇔
  
  139 ✓
- 1.19 × 100 =
  
  ⇔
  
  119 ✓
- 1.35 × 100 =
  
  ⇔
  
  135 ✓
Match the equation to its answer.
- 13 ÷ 10 =
  
  ⇔
  
  1.3 ✓
- 103 ÷ 10 =
  
  ⇔
  
  10.3 ✓
- 103 ÷ 100 =
  
  ⇔
  
  1.03 ✓
- 1,003 ÷ 100 =
  
  ⇔
  
  10.03 ✓
- 1,030 ÷ 10 =
  
  ⇔
  
  103 ✓
Round 9.8 to the nearest whole number.
- 8
- 9
- 10 ✓
Calculate this using short multiplication 48 × 7 = ______
- '336' ✓
Calculate this using short multiplication 126 × 5 = ______
- '630' ✓
Sofia has £93. Lucas has four times this amount. How much money does Lucas have? £______
- '372' ✓

Calculate 4.3 × 5 = ______ Use scaling to convert 4.3 into a whole number.
- '21.5' ✓
Which of these would be the most sensible estimate to check if this calculation is correct? 5.14 × 3 = 15.42
- 5.1 × 3
- 5.2 × 3
- 5 × 3 ✓
- 6 × 3
Calculate 41.8 × 3 = ______
- '125.4' ✓
Calculate 3.27 × 5 = ______
- '16.35' ✓
Lucas has 1.9 litres of water. Sofia has three times this amount. How much water does Sofia have? ______ litres
- '5.7' ✓
Sofia has 2.46 kg of flour. Lucas has three times this amount. How much flour does Lucas have? ______ kg
- '7.38 ' ✓

Use scaling to convert the decimal fraction to a whole number then multiply; use scaling to adjust the product.
If using short multiplication with decimal fractions, align the decimal point in the decimal fraction and product.

The short multiplication algorithm may not be correctly aligned.

Check that the decimal point aligns in the decimal fraction and the product. Scaffolding with place value columns may support further.

Estimation - When we estimate, we find a value that is close enough to the right answer, usually with some thought or calculation involved.
Scaling - Scaling is when a given quantity is made ___ times the size. It can be used to adjust the size of a factor. In this lesson, scaling will involve making values 10 or 100 times the size.