Hundreds-place columns with three addends by default — the stage where neat written method starts paying off.
Three-digit, multi-row addition rewards tidy columns and punishes sloppy ones, which is exactly why teachers assign it. The default here stacks three addends; take it to two for a gentler sheet or push rows higher for endurance work.
Strong students can try the same shape mentally on the practice pages — three-digit running sums are a signature mental-abacus skill.