The natural series and the coordinate ray
Find the number before a given one, find out why there is no largest natural number, mark K(5) on a coordinate ray and read a scale.
- Ukraine: grade 5
Guide
This follows the Ukrainian Year 5 book: section 1, item 1 "The natural series" and item 5 "Scale. The coordinate ray". The child answers by tapping the ray or typing a number.
Natural numbers are the numbers used for counting things: 1, 2, 3, 4, … . The number 0 and fractions are not natural. The natural series has a smallest number, 1, but no largest: every number is followed by one that is 1 more.
A coordinate ray is a ray with an origin O (the number 0) and a unit segment OE. A point's coordinate is written in brackets after its name: K(5). The value of one division can be other than 1, for example 10.