A calculator that shows your workings
A calculator that remembers
Sumthing is a tape calculator for people who think through problems, not just answers. Every calculation stays visible, connected, and editable — change anything and the entire tape updates.
Enter a calculation, commit it to the tape, then tap any result to reuse it in a new line. Edit any number or operator and everything recalculates live. No re-entering formulas — just fix and continue.
Smart tape
Every calculation stays on the tape with its full expression. Results link to each other — change one and dependent calculations update automatically.
Edit anything
Tap any number or operator on the tape to edit it in place. Cancel to revert, clear to remove. All dependent lines update immediately.
Flexible display
Wrap mode shows full expressions across multiple lines. Scroll mode lets you swipe through long formulas. Configure decimal places from 0 to 10.
Designed for focus
Clean dark interface with a muted colour palette, smooth animations, bracket support, and careful handling of negative values.