The learner identifies the immediate predecessor of a whole number within 1–120, understanding that the number before it is one less and is located one step to the left on a number line; this includes transitions such as 20 to 19 and 100 to 99, with 0 recognized as preceding 1. The understanding supports counting, subtraction, and place-value reasoning; negative numbers, fractions, and generalized predecessor rules for arbitrary integers are not included.
To find the number before a number, move one step to the left on a number line. The number before is also one less.
Example: What number comes before ?
So, the number before is .
Remember: the number before is .
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