In the given addition, 6+3=9, 6 is called the augend: a thing to be increased, but this specific term is rarely used. Generally, each of 6 and 3 is called the addend: a thing to be added. Because the commutative law is true in addition: changing the order of numbers does not change their sum, e.g. 6+3=3+6. So, each of 6 and 3 works as an addend.
The sign in the middle,+, is called a plus sign, = is called an equal(s) sign, and 9 is called the sum. Thus, the given addition verbally rendered as "six plus three equals nine."
Be careful not to mix up negative signs in addition with plus signs, e.g. (+)5 + (-)7 = -2. Signs attached 7 and 2 are called negative signs. The addition shown above is rendered as "positive five plus negative seven equals negative two. +5,-7,and -2 are also called signed numbers.
In a subtraction, e.g. 7-5=2, 7: the minuend, 5: the subtrahend, (-): a minus sign, and 2: the difference.
In a multiplication, e.g. 7x5=35. 7: the multiplicand, 5: the multiplier (x): a multiplication sign, and 35: the product.
In a division, e.g. 7÷5=1 R2, 7: the dividend, 5: the divisor, (÷): a division sign, 1:quotient, R(or r.): an abbreviation for remainder, and 2: the remainder.