No. Every result must be a positive whole number. A subtraction cannot reach zero or go below it, and a division must come out exactly.
No. Each step must produce a positive whole number, and the game refuses any step that does not.
What is blocked
- Subtraction: the first number you pick must be larger than the second. 9 − 4 works; 4 − 9 and 5 − 5 (which would give zero) do not.
- Division: the first number must divide exactly by the second. 100 ÷ 4 works; 100 ÷ 7 and 4 ÷ 100 do not.
- Addition and multiplication: always allowed.
You pick a number, an operation and a second number, in that order. A step that breaks a rule is refused and nothing changes, so you can never end up holding a negative number or a fraction.
Using this to your advantage
Because only exact divisions are allowed, a target with many factors is often reached by division or multiplication. Check whether it divides by a number you hold, as the strategy guide suggests. The result of every step replaces the two numbers you used, as covered in whether you must use all six.