2.NBT.B.5 Grade 2 · Number and Operations in Base TenFluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.Common Core State Standards for Mathematics, as adopted in the Massachusetts Curriculum Framework for Mathematics (2017), Grade 2.
Play the game: Place by PlaceStep 49 of the ColorMyMath curriculum · free, no sign-up →Past nine, color tells you which place a digit lives in. A ten is a triangle of ten dots; the number of triangles is the tens digit, so 34 is three triangles and four loose green dots.
Every page is free and open — nothing to install, no account, and it works on a phone or a classroom board. Every number has its own color: 1 red, 2 orange, 3 yellow, 4 green, 5 blue, 6 purple, 7 brown, 8 pink, 9 cyan, and a number is that many colored dots.
Step 49Two-digit addition with easy factsStep 50Two-digit subtraction with easy factsStep 53Two-digit addition with hard facts — carryingStep 55Two-digit subtraction with hard facts — borrowingStep 57Complements of 100: 50+50, 60+40, 70+30, 80+20, 90+10Step 58Complements of 100: 55+45, 65+35, 75+25, 85+15Step 70Two-digit addition with level two factsStep 71Two-digit subtraction with level two facts2.NBT.A.1Hundreds, tens and ones in a three-digit number2.NBT.A.2Count within 1000; skip-count by 5s, 10s and 100s2.NBT.A.3Read and write three-digit numbers: numerals, words, expanded form2.NBT.A.4Compare three-digit numbers with >, = and <2.NBT.B.6Add up to four two-digit numbers: gather the tens first, then the ones2.NBT.B.7Add and subtract within 1000; sometimes tens or hundreds are made or broken2.NBT.B.8Add or take 10 or 100 from a number between 100 and 900 in your head2.NBT.B.9Explain why addition and subtraction strategies workColorMyMath · getridoftheteacher.com · every number has its own color, and a number is that many colored dots. Matching a game to a standard is a judgement call; the official text is at doe.mass.edu.