A bakery packs kaya buns into boxes. Every box holds the same number of buns. There is 1 box, and 3 more buns beside it. Write how many buns there are altogether.
1 box and 3 more = (n + 3) buns
Ans: (n + 3)
Example 1
There are 3 boxes. Write how many buns there are altogether.
Buns in 3 boxes = n + n + n = 3 × n = 3n
Ans: 3n
Example 2
The buns from 1 box are packed equally into 3 bags. Write how many buns are in each bag.
Buns in each bag = n ÷ 3 =n/3
Ans: {n|3}
Example 3
A bakery packs kaya buns into boxes. Every box holds n buns. There are 4 boxes, and 2 more buns beside them. Write how many buns there are altogether.
4 boxes and 2 more = (4n + 2) buns
Ans: (4n + 2)
How to solve it
When a number is not known, give it a letter. Here n stands for the number of buns in 1 box.
Remember that n is the number of buns inside the box. It is not the box.
To add, write the letter and the number: 1 box and 3 more buns is n plus 3.
To multiply, write the number in front and leave out the times sign: 3 boxes is 3 n.
To divide, write a fraction: the buns of 1 box packed into 3 bags is n over 3, which means n divided by 3.
Nobody counted what was inside the box. We gave that number a name instead. And then we could add to it, multiply it, and share it out, just like any other number.
Practice questions with worked solutions
Question 1 is free to try. The other 8 open in the free trial, each with its full working.
How do you write algebraic expressions from words in P6?
This page covers the first two Primary 6 algebra outcomes: using a letter for a number nobody has told us yet, and reading and writing short expressions with that letter.
What your child learns here
This page covers the first two Primary 6 algebra outcomes: using a letter for a number nobody has told us yet, and reading and writing short expressions with that letter. Everything else in the chapter is built on these few marks on paper.
Use a letter, such as n, to stand for an unknown number, and remember the letter is the number inside the box, not the box itself.
Read and write adding and subtracting with a letter: n + 3 and n - 3.
Write multiplication with the number in front and no times sign, so 3 × n becomes 3n.
Write division as a fraction, so n ÷ 3 is written as n over 3.
Turn a sentence into an expression in the order the story happens, and keep the unit outside the brackets, as in (n + 3) buns or $(20 - n).
Does the answer make sense?
When the answer contains a letter, your child can put a small number in its place in both the story and the expression, and the two amounts should agree. Sharing into equal bags or pieces should give less than the amount being shared, while several packets should give more than one packet.
How to practise these questions
Basic questions train how algebra is set down: a number placed in front of its letter, division shown as a fraction, and one operation put into symbols in the correct order. Intermediate questions add money stories in which two operations are chained. Challenge questions ask your child to decide what can be found without knowing the letter, or to handle a pricing rule with leftovers. When writing a letter expression stalls, read the written step-by-step solution.
Questions parents ask
Is algebra in the Primary 6 syllabus? Yes. The MOE syllabus places Algebra in Primary 6 under Number and Algebra, starting with using a letter to represent an unknown number. The later outcomes cover simplifying, substitution and simple linear equations.
Should my child call it a letter or a variable? The Primary 6 syllabus says 'letter', and so do our lessons. 'Variable' is a word your child will meet in secondary school. Either way, the letter stands for a number.
Why is 3 times n written as 3n? Writing the number in front and leaving out the times sign is the usual short form. 3n, 3 × n and n × 3 all mean the same thing, and your child should be able to read each of them.
