**Number Play - Quick Facts**
**1-Digit to 5-Digit Numbers:**
1-digit: 1–9 (9 numbers total)
2-digit: 10–99 (90 numbers)
3-digit: 100–999 (900 numbers)
4-digit: 1000–9999 (9000 numbers)
5-digit: 10,000–99,999 (90,000 numbers)
**Supercells Rule:** A number is a supercell if it is GREATER than ALL its neighbouring cells (left, right, top, bottom).
**Digit Sum:** Add all digits of a number. Example: digit sum of 176 = 1+7+6 = 14.
**Palindromes:** Numbers that read the same forwards and backwards. Examples: 121, 545, 7007.
**Taller Neighbours Game:** Each child says: 0 (no taller neighbours), 1 (one taller), or 2 (both taller).
**Number Line Placement:** Always identify the scale and gaps to place numbers correctly.
**Reverse-and-Add:** Take a number, reverse its digits, add them. Repeat until you get a palindrome (or keep going).
**Diagrams to Remember:** Number lines showing gaps, grid tables with supercells marked, palindrome examples written both ways.
**Don't Confuse:** Digit sum (14) is different from the number itself (may be 68, 176, or 545). A supercell beats ALL neighbours, not just one. Palindromes look identical both ways, regular numbers do not.
Q1. How many 1-digit numbers are there?
Answer: B — The 1-digit numbers are 1, 2, 3, 4, 5, 6, 7, 8, 9, which gives us exactly 9 numbers.
Q2. What is the digit sum of the number 456?
Answer: D — The digit sum is 4 + 5 + 6 = 15.
Q3. Which of the following is a palindrome?
Answer: C — 454 reads the same forwards and backwards, making it a palindrome.
Q4. In the taller neighbours game, what does a child say if neither neighbour is taller?
Answer: A — A child says 0 if neither of the children standing next to them are taller.
Q5. A supercell in a table must have a number that is ___________ than all its neighbours.
Answer: C — A supercell is defined as a number that is greater than all the numbers in its neighbouring cells.
Q6. Which of these numbers has the same digit sum as 68?
Answer: C — 68 has digit sum 6+8=14, and 59 has digit sum 5+9=14, so both have the same digit sum.
Q7. How many 2-digit numbers exist in total?
Answer: A — 2-digit numbers run from 10 to 99, which gives us 99 - 10 + 1 = 90 numbers total.
Q8. On a number line marked with 0, 1000, 2000, where would the number 1500 be placed?
Answer: B — 1500 is exactly halfway between 1000 and 2000 on a number line.
Q9. Which digit appears most frequently when writing numbers from 1 to 100?
Answer: A — The digit 1 appears many times: in 1, 10, 11 (twice), 12-19, 21, 31, 41, 51, 61, 71, 81, 91, and 100, making it the most frequent.
Q10. If you start with the number 19 and apply the reverse-and-add method, what is the result after the first step?
Answer: C — Reversing 19 gives 91, and 19 + 91 = 110.
What is a supercell in the table activity?
A supercell is a number that is greater than all the numbers in the cells next to it (left, right, top, or bottom neighbours).
What does digit sum mean?
Digit sum is the total you get when you add all the digits of a number together.
What is a palindromic number?
A palindromic number reads the same from left to right and from right to left, like 121, 343, or 5005.
How many 1-digit numbers exist from 1 to 9?
There are exactly 9 one-digit numbers: 1, 2, 3, 4, 5, 6, 7, 8, and 9.
How many 2-digit numbers exist?
There are 90 two-digit numbers, from 10 to 99.
In the taller neighbours game, what does a child say if both neighbours are taller?
A child says 2 if both children standing next to them are taller.
Can the largest number in a table always be a supercell?
Yes, the largest number in a table will always be a supercell because it is greater than all its neighbouring cells.
What is the digit sum of 68?
The digit sum of 68 is 14 because 6 + 8 = 14.
What are three examples of 3-digit palindromes using digits 1, 2, and 3?
Three examples are 121, 222, and 313.
In the reverse-and-add activity, what do you do first?
First, you take any number and reverse its digits, then add the original number to its reverse.
What is a supercell? Give one example from the chapter. [1 mark]
A supercell is a number greater than ALL its neighbouring cells. Look at the table examples where numbers are coloured — those are supercells.
Find the digit sum of 345. Is it the same as the digit sum of 543? Why or why not? [2 marks]
Add the digits: 3+4+5. Then add the digits of 543 and compare. The answer shows that digit order doesn't matter for digit sum.
In the taller neighbours game, explain why a child standing at the very end of the line can never say 2. Use a reason to support your answer. [3 marks]
A child at the end has only ONE neighbour (the child next to them), not two. So they can say at most 1 (if that neighbour is taller) or 0 (if not taller). A child needs TWO neighbours to say 2.
Create a 3×3 table of 4-digit numbers where exactly 2 cells are supercells. Explain why those two cells are supercells and the others are not. [5 marks]
Choose numbers so that exactly 2 are greater than ALL their neighbouring cells. The corner and edge numbers have fewer neighbours, while the centre number has 4 neighbours. Show your table and list each number with its neighbours.
True or False: The number 12321 is a palindrome. Give a reason for your answer. [2 marks]
Read the number forwards: 1-2-3-2-1. Now read it backwards. If they are the same, it is a palindrome.
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