It’s widely believed that Indians are really good at math. Even the late Stephen Hawking agreed. New research, however, shows this may not be entirely true.

Students in India manage to perform “simple additions” involving three and four digits with 95% accuracy, but score far lower (69%) while “calculating total bills,” according to a report by QuizNext, a gamified practice app for CBSE (Central Board of Secondary Education) and ICSE (Indian Certificate of Secondary Education) students.

Solving more complex problems like proportions or profit & loss was even more problematic, QuizNext found in its analysis of 120,000 data points collected from over 7,500 students during the month of April.

The kids included in the analysis were enrolled from class 6 to class 10 across over 70 Indian cities.

“The greatest barrier for Indian students in applying math learnings is the notion that ‘a question is out of syllabus.’ We have seen that students are inclined to attempt quizzes that have direct keywords such as ratios or averages, than quizzes where the concepts names are not directly mentioned,” said Chaiitanyaa Naik, head of product at QuizNext, told Quartz. “It is the familiarity that breeds confidence among students.”

Word problems without specific math keywords introduced another layer of difficulty, the analysis revealed.

The issue was pronounced with percentages, for instance. Indian students solved nine in 10 direct problems on percentages such as:

What is 25% of 2000 _______ ?

Convert 1/8 into percentages

However, the accuracy rates dropped significantly when calculating discounts. Just 56% of the time, students managed to answer a question as follows:

Redbus is offering Rs500 cashback on bus bookings of Rs2,000 and above. What the effective discount when you make a booking of Rs2,500?

Inaccuracy is not a language or comprehension issue. “We have a small segment of users who have taken math skill builder quizzes in Hindi. Even those students have struggled with word problems,” said Naik. “Students are more focused on how part of it, than the why aspect, where the primary focus is scoring more marks.”

Geographically, students from Punjab performed the best when data from around 20 states was compared. Maharastra, Bihar, Uttar Pradesh, and Uttarakhand are other states featured in the top five.