+1/−1
Nothing but 0s, +1s and −1s: the math is easy, the speed is what makes it hard. The series are long from the start and flash by much faster than in Classic. A mode to train focus and pace.
How to play
Only 0, +1 and −1 to add up: six from the very first level, and much faster.
Example
1 − 1 + 1 + 0 + 1 − 1 = 1
Tips
- Count the difference rather than the sum: a +1 and a −1 cancel out, only what's left counts.
- Ignore the 0s: they don't change the total, they're there for the pace.
- Don't lose track over a missed number: carry on with the total you have.
Solo or against someone
Solo, go as far as you can: the first mistake ends the game. Against someone, you play the same levels as your opponent: if you're the only one with the right answer, you win. All the rules