  # Florida - Grade 1 - Math - Numbers and Operations in Base Ten - Mental Math - MAFS.1.NBT.3.5

### Description

MAFS.1.NBT.3.5 Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

• State - Florida
• Standard ID - MAFS.1.NBT.3.5
• Subjects - Math Common Core

### Keywords

• Math
• Numbers and Operations in Base Ten

## More Florida Topics MAFS.1.OA.2.4 Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.

MAFS.1.OA.3.5 Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).

MAFS.1.OA.3.6 Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13). MAFS.1.OA.4.7 Understand the meaning of the equal sign, and determine if equations involving addition and subtraction are true or false. For example, which of the following equations are true and which are false? 6 = 6, 7 = 8 – 1, 5 + 2 = 2 + 5, 4 + 1 = 5 + 2.

MAFS.1.OA.4.8 Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = _ – 3, 6 + 6 = _. MAFS.1.G.1.1 Distinguish between defining attributes (e.g., triangles are closed and three-sided) versus non-defining attributes (e.g., color, orientation, overall size) ; build and draw shapes to possess defining attributes. MAFS.1.G.1.2 Compose two-dimensional shapes (rectangles, squares, trapezoids, triangles, half-circles, and quarter-circles) or 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 shape.1 MAFS.1.OA.1.1 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, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem (*Students are not required to independently read the word problems.)

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

• State Test Florida Standards Assessment (FSA)
• State Standards Mathematics Florida Standards (MAFS), Language Arts Florida Standards (LAFS)
• Subject Math
• Topic Name Mental Math
• Standard ID MAFS.1.NBT.3.5
• Description
MAFS.1.NBT.3.5 Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.  