NumberFlow

When you answer a question, the device briefly vibrates to give feedback. This uses the browser's Vibration API, which is not supported by every mobile browser.

• Works: Chrome, Brave, Samsung Internet, and Edge on Android
• Does not work: Firefox on Android (API removed in 2020), DuckDuckGo on Android (API blocked for privacy)
• Not applicable: iOS - Apple does not allow vibration from web pages

If your device supports it, make sure vibration is turned on in your phone's sound or accessibility settings.

Your score is mostly based on how many addition/subtraction items you have mastered.

• Green items are fast, accurate, and consistent across spaced attempts.
• Light green (dashed border) items are "Almost There" - a few more correct answers will turn them fully green.
• Yellow items are still being learned. Every correct answer moves them forward.
• Red items need extra review because of a recent wrong answer, timeout, or slow response.
• A green item can move back down if it later shows weakness, but one typo will not erase your progress.
• Mastered and review-soon items count fully, in-progress items count partly, and accuracy and speed add a small bonus.
• A very strong round - high accuracy and fast speed - can earn a bonus graduation once every item in the stage has been unlocked and answered at least once, even if not all items are fully green yet.

The graph shows your most recent 10 quiz results by default. Use "Show all results" to see your saved Google progress.

The chart zooms in to show progress clearly, but the mastery score is always out of 100.