sum noun The total amount obtained by adding two or more numbers or quantities together. The sum of six and nine is fifteen, which the students wrote in their notebooks. + addend noun A number added to another number in an addition problem. In the equation five plus three equals eight, both five and three are addends. + total adjective Complete or entire; including everything or everyone. The total cost of the trip came to just under two thousand dollars. + plus preposition In addition to; used to show that something is added to another amount or item. The total cost was two hundred dollars plus tax and a small delivery fee. + combine verb To join or merge two or more things to form a single unit or mixture. Combine the flour and sugar before adding the melted butter. + increase verb To become greater in amount, number, size, or degree, or make something greater. The number of visitors increased during the festival. + count verb To determine the total number of items in a group by assigning numbers to them in order. She counted the coins twice to make sure the total was correct. + number line noun A straight line on which numbers are marked at equal intervals, used to show their order and value. The teacher used a number line to show students how to add negative numbers. + regroup verb To gather together again after being scattered or defeated, in order to reorganize. After losing the first set, the team regrouped and came back to win the match. + carry verb To hold and move something from one place to another, or to support the weight of something. She carried the heavy groceries up three flights of stairs without stopping. + digit noun Any of the numerals from 0 to 9 used alone or together to write numbers. The number 4,208 has four digits arranged in a specific order. + place value noun The value of a digit based on its position within a number, such as ones, tens, or hundreds. Understanding place value helps students see why the 3 in 35 means thirty. + equation noun A mathematical statement asserting that two expressions are equal in value. Students learned to solve for x in a simple linear equation. + expression noun A word, phrase, or look that conveys a particular meaning, feeling, or idea. Her puzzled expression clearly showed that she hadn't understood the joke. + estimate verb To roughly calculate or judge the value, size, amount, or cost of something. The contractor estimated that the renovation would take about six weeks to finish. + round adjective Shaped like a circle or sphere, with a curved outline and no sharp corners. The children rolled the round stone down the hill to watch it bounce. + numeral noun A symbol or word used to represent a number. Roman numerals still appear on some clock faces and building cornerstones. + quantity noun An amount or number of something that can be measured or counted. The recipe calls for a small quantity of salt to balance the sweetness. + tally noun A running count or record of a number of things, kept by marking or counting as items occur. He kept a tally of every book he read during the year on a sheet of paper. + group noun A number of people or things gathered, classified, or associated together. A small group of tourists gathered around the guide near the fountain. + pair noun Two things of the same kind used or considered together, or two closely associated people. He bought a new pair of running shoes before the marathon. + double adjective Twice as much or as many, or consisting of two matching or corresponding parts. We ordered a double portion of fries because everyone at the table was starving. + count on verb To rely on someone or something with confidence that they will help or behave as expected. You can always count on your sister to tell you the truth. + missing addend noun In an addition equation, the unknown number that must be found to complete the sum, such as the blank in 5 + ? = 9. To find the missing addend in 6 plus what equals 10, students subtract 6 from 10. + fact family noun A group of related addition and subtraction, or multiplication and division, equations that use the same three numbers. The fact family for 3, 4, and 7 includes 3+4=7 and 7-3=4. + ones pronoun Used in place of a noun already mentioned or understood, to refer to a person or thing of that type. I tried on several jackets and finally chose the blue ones. + tens noun The place value position representing multiples of ten in a number, or the numbers from ten to ninety-nine. In the number 47, the digit 4 sits in the tens place. + hundreds noun The place value in a number representing multiples of one hundred, such as the 4 in 428. In the number 356, the digit 3 sits in the hundreds place. + whole number noun A number without fractions or decimals, such as 0, 1, 2, or 3. Round your answer to the nearest whole number before writing it down. + equal adjective The same in amount, value, status, or rights as something or someone else. The two runners crossed the finish line at exactly equal times. +