“The Great Yoshini” set up a Magic Maths activity on place value. It focussed on finding 1, 10, 100 and 1,000 more and less.
- National Geographic Magic Set
- Base Ten set
- Place Value Disks
- Whiteboards and pens
What is place value?
Place value is the value of each digit in a number. It is important that children understand that while a digit can be the same, its value depends on where it is in the number.
For example, the 5 in 350 represents 5 tens, or 50; however, the 5 in 5,006 represents 5 thousands, or 5,000.
Ioan explained what was involved in ‘Magic Maths’. He had set up four activities. For each Maths problem solved, Finny would unlock a magic trick and also win an elastic band for a fifth and final magic trick.
Challenge 1: Work out the number shown with the base ten and represent it with place value disks, to make the answer magically appear on the purple ball.
Finny had one ‘thousand disk’, three ‘hundred disks’, five ‘ten disks’ and ten ‘one disks’. He explained that if he wrote the numbers 13410 it would make a ‘green disk’ number in the ten thousands: 13 thousand, four hundred and ten. Instead, Finny swapped the ten ‘one disks’ for one ‘ten disk’.
When going to count up the tens, Finny miscounted because his numbers were just scattered in the tens column. By placing the disks in twos, it made it easier to count up the totals of each column.
The answer was 1,460 or one thousand, four hundred and sixty.
Challenge 2: Work out the total of the place value disks, then find the numbers 1,000 more, 100 more, 10 more and 1 more.
Once Finny had solved the questions, Ioan demonstrated that he could stick nails through the coin in his box.
Challenge 3: I have the numbers 5,974 and 5,874. Is the second number 1, 10, 100 or 1,000 less?
If Finny placed the coin on the correct number, then Ioan would make the coin vanish.
Challenge 4: Add one thousand to fix the broken answer.
9,483 (nine thousand, four hundred and eighty three) + 1,000 (one thousand) = 10,483 (ten thousand, four hundred and eighty three)
Final magic trick
Because Finny had completed all of the challenges, he had unlocked all four elastic bands for the final trick.
Finny spent a long time trying to figure out how Ioan had performed the last trick. He’s now keen to start inventing some more magic tricks of his own.
DfES National Curriculum (2013)
Numeracy Year 4 programme of study
Number – number and place value
- count in multiples of 1000
- find 1000 more or less than a given number
- recognise the place value of each digit in a four-digit number (thousands, hundreds, tens, and ones)
- order and compare numbers beyond 1000
- identify and represent numbers using different representations
- solve number and practical problems that involve all of the above and with increasingly large positive numbers