Mad Add is a numerical logic puzzle. You're given a grid full of single-digit numbers. On the right of every row sits a target sum for that row, and on the bottom of every column sits a target sum for that column. Your job is to delete the right numbers — and only the right numbers — so that what remains in every row, and every column, hits its target at the same time. There is no arithmetic; there's no rearranging. Just decide which numbers stay and which numbers go.

✏️ Tapping a Cell

Each cell has three states. Tap an undecided cell once to delete it — a red ✕ appears and the number stops counting. Tap a second time to lock it as kept — a small green ✓ pins it in. Tap a third time to clear back to undecided. As soon as a row or column hits its target it turns green ✓. If it goes over the target, it pulses red — you've kept too much and need to delete more.

⚡ The Smart Target Shortcut

When you've locked enough cells in a row that their sum already equals the target, the target badge glows gold and starts to pulse. Tap the glowing badge and the rest of that row's undecided cells get auto-deleted in one step — a satisfying time-saver for the endgame. The same shortcut works for columns. It's an undoable action like any other.

💡 Hints (Hybrid Model)

Stuck? Hit the 💡 hint button. The first three hints are free — each reveals one correct cell. After that every hint adds +30 seconds to your timer, so you can keep going but it costs you a fast time. The little badge on the hint button always shows what's left or what the next one will cost.

📊 Grid Sizes & Difficulty

Two independent dials let you tune the challenge. Pick a grid size from 5×5 up to 11×11, then set a difficulty from Beginner through Cyborg ☠. Every size offers all seven difficulties, so a quick 5×5 Beginner is a gentle warm-up and an 11×11 Cyborg is a serious workout. Harder difficulties demand more deletions to solve and at the top tiers the puzzle is verified to have exactly one valid solution — no guessing.

Play Mad Add free online — no download, no sign-up. Mad Add is a browser-based math puzzle game that runs on any device. Work through 7 difficulty levels across 7 grid sizes, take on the seeded daily challenge to grow your streak, and share your time to challenge friends with the same puzzle.

The daily challenge resets every midnight and is the same puzzle for every player worldwide on that date. Build a streak, beat your personal best across sizes, and use the challenge link to send any specific puzzle to a friend.

• Scan tight rows first. If a row's target is very low or very high, only a few combinations of cells can possibly satisfy it — those are the easiest to lock in.
• Use locks aggressively. Locking cells you're confident about (state ✓) lets the smart-target shortcut kick in later and saves you taps.
• Watch the badges. When a row badge starts glowing gold, you're one tap away from finishing the whole row.
• Combine row and column logic. A cell that would push its column over the target probably has to be deleted, even if its row could still take it.
• Save hints for the endgame. The first three hints are free — but using them late, when you're stuck on the last 2–3 cells, gives you more information than using them at the start.