Topics › KS3 › Number

Place value & ordering decimals

  1. What is the value of the 7 in $3.072$?

    Option A: 7 tens
    Option B: 7 tenths
    Option C: 7 hundredths
    Option D: 7 thousandths
    Answer and misconceptions
    Option A: 7 tens ✗
    Ignores the decimal pointReads 3.072 as 3072, so the 7 is in the tens column.
    Option B: 7 tenths ✗
    Ignores the zero placeholderSkips the 0 and treats the 7 as the first digit after the point.
    Option C: 7 hundredths ✓ Correct
    Option D: 7 thousandths ✗
    Counts the decimal point as a columnTreats the point as the tenths place, pushing every digit one column right.
  2. Which number is the largest?

    Option A: $0.6$
    Option B: $0.0625$
    Option C: $0.098$
    Option D: $0.62$
    Answer and misconceptions
    Option A: $0.6$ ✗
    Thinks fewer decimal places means largerBelieves tenths beat hundredths, so the shortest decimal must be biggest.
    Option B: $0.0625$ ✗
    Reads digits after the point as a whole numberCompares 6, 625, 98 and 62 as whole numbers; 625 wins.
    Option C: $0.098$ ✗
    Ignores a zero straight after the pointReads 0.098 as 0.98, so thinks it is the largest.
    Option D: $0.62$ ✓ Correct
  3. Work out $3.06 \times 10$

    Option A: $30.6$
    Option B: $3.060$
    Option C: $306$
    Option D: $0.306$
    Answer and misconceptions
    Option A: $30.6$ ✓ Correct
    Option B: $3.060$ ✗
    Multiplies by 10 by adding a zero on the endUses the whole-number shortcut, which does not change a decimal's value.
    Option C: $306$ ✗
    Thinks multiplying by 10 removes the decimal pointDrops the point instead of moving digits one place left.
    Option D: $0.306$ ✗
    Moves digits the wrong way when multiplyingShifts digits right (dividing by 10) instead of left.
  4. Work out $52 \div 100$

    Option A: $5.2$
    Option B: $0.52$
    Option C: $0.052$
    Option D: $5200$
    Answer and misconceptions
    Option A: $5.2$ ✗
    Moves digits one place for dividing by 100Treats every division by a power of ten as dividing by 10.
    Option B: $0.52$ ✓ Correct
    Option C: $0.052$ ✗
    Moves digits one place per digit of 100Counts the three digits in 100 and shifts three places instead of two.
    Option D: $5200$ ✗
    Adds zeros instead of dividingUses the "add zeros" shortcut for multiplying, even though this is a division.
  5. Which list puts $3.7,\ 3.65,\ 3.802$ in ascending order (smallest first)?

    Option A: $3.7,\ 3.65,\ 3.802$
    Option B: $3.802,\ 3.65,\ 3.7$
    Option C: $3.802,\ 3.7,\ 3.65$
    Option D: $3.65,\ 3.7,\ 3.802$
    Answer and misconceptions
    Option A: $3.7,\ 3.65,\ 3.802$ ✗
    Thinks longer decimals are largerOrders by number of digits after the point, like whole numbers.
    Option B: $3.802,\ 3.65,\ 3.7$ ✗
    Thinks shorter decimals are largerBelieves more decimal places means smaller pieces, so the longest is smallest.
    Option C: $3.802,\ 3.7,\ 3.65$ ✗
    Confuses ascending with descendingOrders the decimals correctly but largest first.
    Option D: $3.65,\ 3.7,\ 3.802$ ✓ Correct
  6. Work out $0.6 \div 0.02$

    Option A: $30$
    Option B: $0.3$
    Option C: $0.012$
    Option D: $3$
    Answer and misconceptions
    Option A: $30$ ✓ Correct
    Option B: $0.3$ ✗
    Divides the digits and keeps the decimal places of the first numberWorks out $6 \div 2 = 3$ and gives it one decimal place like $0.6$. Dividing by a number less than 1 makes the answer bigger.
    Option C: $0.012$ ✗
    Multiplies instead of dividingWorks out $0.6 \times 0.02 = 0.012$.
    Option D: $3$ ✗
    Multiplies the two numbers by different powers of 10Changes $0.6$ to $6$ (×10) but $0.02$ to $2$ (×100). Both must be multiplied by the same amount: $60 \div 2 = 30$.