Mentally adding tens to 3-digit numbers

Mentally add and subtract a three-digit number and tens

Usually learned at ages 7–8

Builds on: The three digits of a three-digit number, 10 or 100 More or Less

Nothing here yet in this language. Add the first explanation with your AI.

On the map from: Marble Skill Taxonomy (v1), © Generative Spark, Inc. (withmarble.com), text CC BY-SA 4.0, database ODbL 1.0: https://github.com/withmarbleapp/os-taxonomy