SMO Junior · 6. Digits and number construction
Write numbers by place value, use digit sums, last digits and carries, and solve letter sums and joined-number problems.
Write digit conditions as equations using place value.
Use digit swaps and reversals, whose changes are multiples of 9.
Work with digit sums, carries and the last digits of large sums.
Solve letter sums column by column.
Solve joined-number problems with a factor trick and write a complete proof.