  # Kentucky - Grade 1 - Math - Numbers and Operations in Base Ten - Mental Math - KY.1.NBT.5

### Description

Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

• State - Kentucky
• Standard ID - KY.1.NBT.5
• Subjects - Math Common Core

### Keywords

• Math
• Numbers and Operations in Base Ten

## More Kentucky Topics Understand the two-digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: a. 10 can be thought of as a bundle of ten ones — called a “ten.” b. The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight or nine ones. c. The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight or nine tens (and 0 ones). Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart and comparing, with unknowns in all positions. Apply properties of operations as strategies to add and subtract. Distinguish between defining attributes versus non-defining attributes; build and draw shapes to possess defining attributes. Compose shapes. a. Compose two-dimensional shapes to create rectangles, squares, trapezoids, triangles, half-circles and quarter-circles composite shape and compose new shapes from the composite shapes. b. Use three-dimensional shapes (cubes, right rectangular prisms, right circular cones and right circular cylinders) to create a composite shape and compose new shapes from the composite shapes.

## Here is the skill that Kentucky requires you to master

• State Test K-PREP
• State Standards Kentucky Core Academic Standards
• Subject Math
• Topic Name Mental Math
• Standard ID KY.1.NBT.5
• Description
Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.  