# 4.NBT.4. Fluently add and subtract multi-digit whole numbers using the standard algorithm

Addition - Crystal Crash

A fun game to practise mental addition skills. The game was designed to cover all the mental addition objectives in the new math curriculum. You can choose one objective, or choose all the objectives for a year group.

This game, together with all the other crystal crash games, is available as a single iPad or Android app.

Subtraction - Crystal Crash

The game was designed to cover all the mental subtraction objectives in the new math curriculum. You can choose one objective, or choose all the objectives for a year group.

This game, together with all the other crystal crash games, is available as a single iPad or Android app.

 1) Subtract numbers from up to 10 (Y1) 6) Subtract from 100 (multiples of 10) (Y3) 11) Subtract tens from a three-digit number (Y3) 16) Subtract combinations of decimals (1dp) (Y4) 2) Subtract numbers from up to 20 (Y1) 7)Subtract from 100 (multiples of 5) (Y3) 12) Subtract hundreds from a three-digit number (Y3) 17) Subtract a decimal (2dp) from 1  (Y5 & Y6) 3) Subtract ones from a two-digit number (Y2) 8) Subtract from 100 (Y3 & Y4) 13) Subtract a decimal (1dp) from 1 (Y4 & Y5) 18) Subtract combinations of three-digit numbers (Y5 & Y6) 4) Subtract tens from a two-digit number (Y2) 9) Subtract from 1000 (multiples of 100) (Y3 & Y4) 14) Subtract a decimal (1dp) from 10 (Y4 & Y5) 19) Subtract combinations of decimals (2dp) (Y5 & Y6) 5) Subtract a two-digit number from a two-digit number (Y2) 10) Subtract ones from a three-digit number(Y3) 15) Subtract two-digit numbers from three-digit numbers (y4)
Addition - Digit Drag

Drag the digits to make a given sum. Lots of choice over level. A great starter activity for discussions on place value, mental methods of calculations and problem solving.

Balancing Sums

An excellent tool for reinforcing an understanding of the role of the equals sign. Choose one objective, or many. You can choose all the objectives for a single year group (or multiple year groups). You can also choose to balance between different types of calculations (eg addition and multiplication).

Balancing Scales g and kg

Add weights to either pan until they are balanced. Can be used to teach addition, subtraction, partitioning, and mass, as well as developing an understanding of the equals sign.

Choose from grams, whole kilograms or kilograms with either 1 or 2 decimal places.

Number Facts Beat The Clock

Score as many points as you can before the time runs out. A number of levels including addition, subtraction, multiplication, division and matching fractions and decimals.

*Updated 30th May 2013 - choose multiple objectives, or objectives grouped by national curriculum level. The game also now includes a scoreboard. An iPad version is also available.

For more multiplication and division resources click here.

Balance scales - add, move or remove a weight

Balance the scales by adding, moving or removing a weight. A great mental starter to develop addition and subtraction skills.

Missing Digits

Find the missing digit in a calculation. Choose addition, subtraction, multiplication or division. Lots of control over level inculding decimals.

For more multiplication and division resources click here.

Addition Pairs - Rapid Recall

A great way to practice number bonds / complementary numbers. Play against the clock and see who can complete the sums quickest. Choose number pairs that equal 10, 20, 50 or 100, or decimals pairs that equal 1.

Difference using an unmarked number line

Find the difference between two numbers by counting on from the smaller number to the larger number. Children must add the fewest numbers possible, so are encouraged to develop more efficient mental methods. The addition is also shown as jumps on a number line.

Levels include counting up to 10, 20, 50 or 100, finding the difference between 2-digit numbers, 3-digit numbers and decimals.

Ordering Calculations

Order the calulations from those with the least value to the greatest. Lots of levels, including; addition pairs to 20, addition pairs to 100, addition and subtraction of multiples of 10, and multiplication of numbers up to 10.

For more comparing and ordering resources click here.

Add the partitioned numbers beginning with the largest. Choice of 2-digit, 3-digit or 4-digit numbers. An important conceptual step before a more formal method of column addition.

This game is now part of the 'Calculations' collection, which includes the following 17 games and resources: Column Addition, Expanded Addition, Expanded Addition - Place Value Counters, Number Bonds(2), Addition - Digit Drag, Missing Symbols, Column Subtraction, Column Subtraction using Place Value Counters, Counting on to find difference on a beadstring, Multiplication Grid Method, Multiplication Written Method, Ratio and Scaling Numbers, Representing Multiplication, Division by Chunking Up, Division by Chunking Down, Formal Written Division - Round Up or Down?, Short Division Writen Formal Method.

The Calculations app is available on Google Play and the App Store.

The next step towards an efficient formal method of column addition. Add the numbers starting with the least significant, then combine the partitioned result. Choice of 2-digit, 3-digit or 4-digit.

This game is now part of the 'Calculations' collection, which includes the following 17 games and resources: Column Addition, Expanded Addition, Expanded Addition - Place Value Counters, Number Bonds(2), Addition - Digit Drag, Missing Symbols, Column Subtraction, Column Subtraction using Place Value Counters, Counting on to find difference on a beadstring, Multiplication Grid Method, Multiplication Written Method, Ratio and Scaling Numbers, Representing Multiplication, Division by Chunking Up, Division by Chunking Down, Formal Written Division - Round Up or Down?, Short Division Writen Formal Method.

The Calculations app is available on Google Play (£1.25) and will be available in the App Store in July.