A blood donor is someone who wants to donate their own blood to people in need without any element of coercion from anyone. Predicting the number of blood donors is very important and necessary to find out the number of blood donors in Langkat Regency in 2023-2024, and the prediction results can help PMI Langkat Regency in increasing the number of blood donors. The method applied in this prediction system is Linear Regression, where this analysis determines whether or not each variable is in accordance with the prediction results being tested and estimates that the value of the variable will increase or decrease each month. The prediction system is carried out using the RapidMiner application because this application is very appropriate for producing information output in the form of prediction results for the coming year. The prediction results obtained by testing using the Linear Regression method show increases and decreases every month. There are 11 months where there has been an increase and decrease in the predicted results and are in accordance with the data in 2023, then there is 1 month which has decreased in the predicted results and does not match the data in 2023. From the overall data results, it can be calculated the number of blood donors in Langkat Regency in 2023 and every month. Measuring the error level of prediction results using RMSE, the resulting accuracy level was 83.574%.

In today's digital era, advances in technology and science are growing very rapidly. Of course, advances in technology and science affect various things. One of them android-based gadgets is utilization to make it easier to find information or knowledge that can be easily accessed. This research aims to design and create an application for the introduction of endemic animals in Indonesia. Endemic animals are species that only exist in certain places and are not found in other places, such as islands, countries, or other geographic areas. Android is an operating system that has an open source nature that allows it to make it easier to recognize and access information about Endemic Animals in Indonesia. The research method for designing and making applications uses the Software Development Life Cycle (SDLC) method. The method begins with planning, analysis, design, implementation and testing. The final result of this research is an application for the introduction of endemic animals in Indonesia based on android. This application was successfully made with appropriate material and quiz features. Function testing on each feature is done with the black box method to ensure the material runs well to display images and material and the function on the quiz feature can function properly. Tests were also conducted with 3 android devices with different versions, namely versions 10, 12, and 13.

Dementia is a growing global health challenge due to the aging population and lifestyle changes. Early and accurate diagnosis is crucial but often difficult and costly. The Case-Based Reasoning (CBR) method in artificial intelligence offers a solution by mimicking human problem-solving based on past experiences. This study aims to develop and implement an efficient and reliable CBR-based dementia diagnosis system. The system is expected to analyze and compare patient symptoms and medical histories with documented cases to provide faster and more accurate diagnostic recommendations. The implementation of CBR in a web-based expert system using PHP and MySQL has proven effective, significantly contributing to the improvement of patient quality of life and healthcare system effectiveness.