Fractions help
Adding and subtracting fractions
Adding and taking away fractions is straightforward when both fractions have the same bottom number. When the bottom numbers are different, you need one extra step first.
What this looks like in the game
You tap a fish and see a question like "Work out 1/3 + 1/4." You drag tiles to build the answer — a single fraction, fully simplified.
Same bottom numbers
When the bottom numbers match, just add or take away the top numbers. The bottom number stays the same.
1/5 + 2/5
Bottom numbers are both 5, so: 1 + 2 = 3. Answer: 3/5.
7/9 − 4/9
7 take away 4 = 3. Answer: 3/9. But 3/9 simplifies to 1/3. Always simplify.
Different bottom numbers
When the bottom numbers are different, you need to rewrite both fractions so they have the same bottom number first.
Worked example 1 — same bottom numbers
Bottom numbers match — both are 7. 3 + 2 = 5.
Answer: 5/7. Already simplified.
Worked example 2 — different bottom numbers
Find common bottom number
3 × 4 = 12
Rewrite 1/3 as twelfths
1 × 4 = 4 · so 1/3 = 4/12
Rewrite 1/4 as twelfths
1 × 3 = 3 · so 1/4 = 3/12
4/12 + 3/12 = 7/12
Simplify
Nothing divides into both 7 and 12. Answer: 7/12.
The most common mistake
Watch out for
Adding the bottom numbers instead of finding a common one.
Wrong
1/3 + 1/4 → add the bottoms → 2/7.
You cannot add the bottom numbers.
Right
Find 12 (3 × 4), rewrite both fractions, then add the top numbers: 4/12 + 3/12 = 7/12.
Think of it this way: you cannot add thirds and quarters directly, just like you cannot add centimetres and metres without converting first.
Which game stage uses this
This is the Adding and subtracting stage. You'll start seeing questions like these when you reach the angelfish and blue tang in the game.