What do the three "?" faces add up to?
A normal-level "Count" problem.Hunting for which faces are opposite means fresh work for every net. Subtracting from the fixed total of 21 sidesteps the shape entirely.
GivenThe net of a dice. Opposite faces always add up to 7.
Hints
- A dice has six faces, and opposite faces always come in pairs — so there are three pairs (1-6, 2-5, 3-4).
- Each pair adds to 7 and there are three of them, so 7 × 3 = 21. That is the total of all six faces.
- The three visible faces are 2, 3, 1, which add to 6.
- The remaining three are just the total minus what we can see: 21 − 6 = 15.
- Look back: we never once worked out which face is opposite which. So this method works whatever shape the net takes.
Answer 15
More "Count" problems
- How many turns does the small circle make?
- How many cubes have 2 painted faces?
- Into how many pieces do 4 lines cut the paper?
- In how many ways can the three chosen rods form a triangle?
- How many triangles are there in the figure?
- How many squares are there altogether?