Answer: How much is 20,000 plus 10,000? It is the mathematics content of the third grade of primary school, and the addition and subtraction within 10 thousand. Calculated in ten thousand units, it is twenty thousand 1 ten thousand = thirty thousand. Calculate by numbers. 2000 o1010000 = 300 o0. When calculating, be sure to read the figures clearly and don't be careless. 210,000 1 10,000, first calculate 200 1=3, then fill in 10,000 words. The handwriting is neat.