An elephant eats a meal of lettuce, apples,bread, carrots and bananas. A Japanese researcher has said that Asian elephants can do mathematics, proving their skill at addition in an experiment with their favourite food. [File Photo: AFP]

Asian elephants can do mathematics, proving their skill at addition in an experiment with their favourite food, a Japanese researcher said Monday.

One elephant was 87 percent correct and the other 69 percent right in months of addition exercises involving single digits, according to Naoko Irie of the University of Tokyo.

In one test, researchers dropped three apples into one bucket and five into another bucket and then added two apples to each.

Five times out of six, Ashya, a 30-year-old female elephant at Tokyo's Ueno Zoo, chose the bucket with seven apples rather than five although she could not see or feel the inside of the containers.

The other elephant, 38-year-old Mito from the western city of Kyoto, was also right five times in a test involving oranges.

Irie, a doctoral candidate in cognition and behavioural science, said she was surprised at the elephants' mathematics skills.

"I couldn't believe it at first," Irie told AFP. "They could instantly compare numbers like six and five."

Each animal was tested using their favourite food. Elephants have roughly the same life span as humans.

Many animals are known to be able to choose the bigger of two numbers. Their performances, however, usually decline if the numbers are big or the gap between two numbers is small.

But the two elephants maintained a good showing with larger numbers and slim margins.

Ashya was correct in five out of six tests on the addition of five-plus-one and three-plus-four, which means the margin of only one apple. Mito was four times right on the same assignment, she said.